How to safely delete files from a hard drive and ssd

If you were trying to delete sensitive data from your hard drive or SSD, a malicious person could recover your files using data recovery software or Windows file history. What to do then to permanently delete a file from your hard drive? Follow our elaborate guide to rest easy.

Index of contents

How to Safely Delete Files on HDD and SSD

Let's imagine you want to permanently delete a file that contains sensitive data like work documents, your bank details, administrative information, financial documents, a private conversation, or something else. In short, the things that you want to eliminate forever and that nobody finds.

How are you going to delete these files?

Normally, you send the file to the Recycle Bin, and then empty it completely. Faster, you can also select the file from Windows Explorer and press Ctrl + Del to delete it without going through the Trash.

Using this method, you get the impression that your file is permanently deleted. However, it still physically exists on the HDD or SSD.

A file occupies a specific space on the disk, so when you delete a file from the Recycle Bin, the file system (the library that organizes and stores the files on disk) simply tells Windows that the space occupied by That file was left free and can be used to store another file instead. The file system only deletes the reference in the file table, but not the file itself.

An "X" file will remain on the HDD or SSD until another "Y" file is created and placed in the space occupied by this old "X" file. And even after that, it is still possible to recover the data from the old file by studying the magnetic fields on the surface of the hard drive tray.

In short, when you delete a file from the Recycle Bin, the file's data is not removed from the disk, but simply waits to be replaced.

The solution is to write random data to the disk space where the old file was located. Therefore, nobody will be able to recover your file because only the random data written on said file will be visible.

What happens to a file when it is deleted?

We leave you the two most common cases:

Hard disk drives (HDD)

When you delete a file on an HDD, it goes to the Recycle Bin. This gives an opportunity to recover it in case it has been accidentally deleted and is needed again.

But what happens when it is removed from the Recycle Bin? Not much really. The file does not move or go anywhere. In fact, when you moved it to the Recycle Bin, it didn't physically go there either. All that happened was that an index was updated to say that the file is in the Recycle Bin, not in the Documents folder.

The index is called the Master File Table (MFT) for hard drives.

Until the operating system puts data there, the data in the deleted file will remain recoverable. It may take minutes, days, weeks, or months for the data to be overwritten.

Solid State Drives (SSD)

It is not exactly the same for solid state drives. SSDs are always moving files randomly. So figuratively, if you delete a file from location 2781, the deleted information may, sooner or later, be moved to another random location, until at some point the SSD finally decides to overwrite that file.

So how do you select the old file to be safely deleted on an SSD?

Well, you really can't. A group of engineers at the University of California studied how difficult it is to erase data from an SSD. What you can do is make sure that you encrypted your SSD and that you have a TRIM-capable SSD.

This is not a problem for most people, but you may be concerned that people may still be able to access that deleted information.

The least secure erase method

Simply delete the file in Windows Explorer and empty the Recycle Bin. Unless you think someone will come up with data recovery software and search for that file at some point, this will probably be pretty safe for most people.

However, this is the easiest way to leave the deleted files on your disk and that can be found through specialized software. We already made this clear at the beginning of the article, right? ?

Software to delete files on an HDD

To do this, you must use file destruction software. There are several, but if I recommended one to permanently erase your files, it would be Eraser. By default, Eraser uses the Guttmann algorithm, which writes patterns several times in the space that contains the data to destroy. This algorithm ensures that your data cannot be recovered.

We leave you a small tutorial on how to permanently delete a file or a folder, with the free Eraser software. Here we go!

Simple erase with Eraser

Simple removal from Windows Explorer: Removal starts immediately or when Windows is restarted, using the default removal method and the right mouse button, selecting "Erase" and "Options".

An information bubble will appear in the notification bar once the file has been permanently removed from the hard drive.

Advanced erase with Eraser

Advanced deletion by creating a task from the Eraser interface. This method offers more possibilities: choose the deletion method, schedule the deletion of a file at a specific date and time, choose the type of items you want to delete (file, folder, trash, unused disk space and more).

Before you start deleting a file and whichever method you choose, go to the Eraser settings to define the deletion method.

In the default file deletion method, choose the default delete method for your files and folders. The deletion methods are classified from top to bottom, from the most efficient (Gutmann - 35 passes) to the most superficial (Pseudorandom Data - 1 pass).

With the Gutmann method, you are sure that your data will be completely erased from the hard drive, making it impossible to recover. However, this method takes a long time since 35 passes are made in the area to be erased. In contrast, the Pseudorandom Data method is very fast, but it does not guarantee a permanent deletion of your data.

In the default unused space erase method, choose the default erase method to apply to unused disk space (feature available with advanced erase).

Open Eraser, click the arrow to the right of the "Erase Schedule" option and select "New Task" (shortcut: Ctrl + N).

• You must define the following properties: Task name (optional): this is the name you want to give your task, and it is optional.Task Type: when you want to execute the task, being able to choose between manual, immediate, on restart or recurring.Data to erase: data to be permanently erased. If you select “Recurring” to delete files according to a program, go to the “Schedule” tab to set the program settings and select when to start deleting: Daily (all days), Weekly (every week) or Monthly (every month).

On the "Task" tab, click the "Add data" button to select the items you want to remove:

• File: a specific file. Files in folder: all files in a folder. Check the Delete folder if empty box to also delete the folder and not just its contents. Unused disk space - Unused disk space on your hard drive. We have seen before that a free space does not mean that there are no files on the hard disk, simply that these files are waiting to be replaced by later files. Recycle Bin: Recycle Bin itself. Secure move: move the file to another location and without traces.Drive/Partition: select the partition you want to delete.

You can also select the deletion method in "Erasure Method".

Double-click OK to confirm the final deletion of the data, depending on the options you have just defined. Eraser tells you on its interface when the tasks will be executed next time (in the Next Execution column).

If you have decided to manually delete a file or folder, you should start deleting by right-clicking on the task and selecting Run Now.

The status of the task changes to Completed when the files are deleted.

Other applications to delete files on an HDD

With their hard drives, some people try to recover deleted data, for example with softwares like Recuva. Others point to the exact opposite: ensuring that deleted files are no longer recoverable at all. For this, there is nothing better than resorting to secure erase software.

Thanks to the type of software, not only are the files and folders that are basically deleted no longer recoverable, but the formatted and partitioned drives also lose all traces of your old data. At least that's what the developers promise.

Clean Disk Security

It is a shareware (the license costs $ 19) whose interface (in English) facilitates the realization of a set of secure deletion tasks. Simply check the desired options (out of a total of ten), choose the method and click the "Clean" button.

As in Eraser, there is the “Clean standard free space” function, but apparently no function to safely delete existing files. For security reasons, the developer has chosen to install this option in the Windows context menu, by right-clicking on a file or folder.

Clean Disk Security also provides a tool to view the contents of each sector of the disk from the "View" button, a slightly more technical option that may be useful.

Prevent Restore

It is the free version of the Prevent Restore Pro software, which costs about $ 14.95. In this lighter version, only one deletion algorithm is proposed, which consists of replacing the deleted data with spaces.

The software is easier to use than Clean Disk Security, and even easier than Eraser, since you only need to answer the questions of a wizard to start a safe removal procedure.

Keep in mind that here you can only permanently delete what has already been removed: if necessary, you must remove the content you want to remove before starting the software.

Despite its limited functions and erase methods, Prevent Restore is an interesting option that may be sufficient within a company, for example to clean a reconditioned workstation to move it from one department to another.

Activate @ KillDisk

As its name clearly indicates, Active @ KillDisk is software that does not want to give any chance to the data. Its specialty is secure erase, with more than 20 algorithms and a wide range of functions, options and settings.

Active @ KillDisk is offered by its developer in two editions: one free, allowing you to discover the software and perform simple deletions in one go; and the other paid (PRO), sold with various types of licenses for individuals and companies, which contains everything you need and much more.

The best way to get an idea of ​​the many features it offers is to install the free version. The interface is in English, as well as the 52-page PDF manual that can be viewed quickly by pressing F1. A useful read.

CCleaner

If you know CCleaner, you will probably know that it is not a secure deletion software, but a Windows optimization tool. It is used in particular to delete (in a traditional way) temporary files from browsers and to optimize the Windows Registry.

CCleaner is however an interesting option here as it is equipped with a disk erase module. What may be sufficient for your needs.

Here everything is very simple: you choose what to delete (free space or all), how (with a simple to very complex algorithm, from 1 to 35 passes) and where (in what unit). And that's it.

The advantage of choosing CCleaner to secure hard drives is that the software is available in a portable version. You can copy CCleaner Portable to a USB memory and thus have a deletion tool ready to use in your pocket and just a click away.

Also, the interface is in Spanish.

Erase files on solid state drives

Solid state drives (SSDs) are becoming increasingly popular and it seems like it is only a matter of time until they replace conventional hard drives in computer systems.

SSD drives work differently than hard drives, especially when it comes to drive read and write processes. The most efficient way to safely delete on hard drives (overwriting space with data) becomes unusable on SSD drives due to its design.

Data on hard drives can be erased by overwriting them. This ensures that the data is not recoverable by the data recovery tools. This method does not work on SSD drives as it is not possible to specify the location to overwrite.

This is highly problematic for computer users who want to give away their computer or sell it to a third party, as the data on the SSD can be recovered by the new owner.

But for SSDs there are also erase methods:

• Manufacturer's Official Utilities PartMagic Delete Files Format SSD

Manufacturer's official utilities

Deleting any trace from an SSD is more complicated. However, also in this case we can use different methods. The first is to use the SSD manufacturer's utilities.

Each manufacturer of SSDs includes software with their products to be able to manage data and disk functions. These are the main utilities that SSD manufacturers include:

• Solid State ToolboxCorsair SSD ToolboxSanDisk SSD ToolboxSamsung Magician SoftwareOCZ Toolbox

Using Parted Magic

Another way to delete data on an SSD is Parted Magic. This is very effective software that costs around 12 dollars.

Delete files

This is a direct way to delete files on the solid state drive from the operating system. It is the only option that can be used to selectively delete files and folders.

Deleting files directly in Windows Explorer is not enough to protect data from recovery software, as software like Recuva can find almost 100% of files that have been deleted in Windows Explorer.

Deleting files directly from the operating system is therefore not an option to permanently delete sensitive data on solid state drives.

Formatting the Solid State Drive

This is the easiest option, as it can be run directly without the need for additional software. Windows users should locate the SSD in Windows Explorer, right click on it and select "Format" from the available options.

It is important to uncheck the "Quick Format" option to make sure that all the data on the drive is formatted.

Windows Explorer does not display any files on the drive once the full format has been completed.

Recommended method to erase data on SSD

Many recommend formatting the solid state drive as it is the easiest method of all. In general, it is not necessary to encrypt the data on the drive before formatting it, as it produces the same results as performing standard formatting.

It is highly recommended to test the result with file recovery software to make sure that the leftover data cannot be recovered.

conclusion

In this tutorial we saw several methods that allow you to permanently delete a file or folder from an HDD or SSD.

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Don't hesitate to use them if you sell a computer that contains sensitive data, personal photos, administrative or bank documents. Otherwise, the future owner could recover all your data even if you formatted the storage device. As a last option you have the option of drilling the hard disk… although I think very few (except that you are a company) choose this method