How do I erase my hard drive

Permanently delete data from the hard disk

Roland Freest

Deleting files doesn't seem to require much attention. But when checking, the process turns out to be quite complex. It is particularly important to proceed carefully if you want to dispose of or sell a data carrier.

A short press on the "Del" key - and the file is gone. Every computer user knows and does this, sometimes even several times in one day. Some also prefer the mouse, click the file with the right button and select "Delete" in the context menu. Alternatively, you can simply drag the content to be deleted into the trash. In any case, deleting is one of the first things users learn when they become familiar with the computer. Everyone understands what is happening - or at least believes it.

However, deleting it is actually quite a complicated affair and you have several options. Which form of deletion is the best or most suitable in which case must be clarified in advance: Why do you want to delete a certain file or several files at all? Because there can be several reasons for this:

  • You no longer need the content and want to provide a better overview on your computer.

  • You want to free up space because the free space on the hard drive is running out.

  • You want to dispose of an old hard drive or SSD and first remove all confidential data from it.

Depending on what applies to you, you should proceed differently when deleting. Because every operating system supports different ways of removing files and folders. There is also another important technical aspect: If you want to securely delete files and their contents, you have to differentiate between conventional magnetic hard drives and SSD flash drives (see box below).

Hardware trends 2019:Hard drives & SSDs

Out of sight: move files to the trash

If you delete files, folders or, for example, desktop icons in Windows, they automatically end up in the recycle bin. In this way they have not really disappeared or even deleted, rather the operating system has simply moved them to a separate folder.

To get them back, open the recycle bin with a double click, mark the desired content, click with the right mouse button and select "Restore". The file then reappears in its original location. The recycle bin therefore represents a security function that is intended to protect the user from accidentally deleting any data that is still required.

Only when you right-click on a file or the entire recycle bin and select “Delete” or “Empty Recycle Bin” is the data actually “gone”. But be careful, the Windows Recycle Bin does not react as described in all situations. Because if you remove data from a connected computer via the network, it is deleted immediately and does not appear in the recycle bin on either your computer or the other. Even when deleting files with the “del” command in the command prompt, the files immediately end up in nirvana. And if a file is larger than the set size of the recycle bin - to check it, right-click on the recycle bin icon and call up "Properties" - it will also be deleted immediately. If the waste bin is full to the brim, the oldest content is automatically thrown out and overwritten when new files are added.

EnlargeWith Anti-Twin you can search specifically for copies of confidential files.

The normal deletion process in the recycle bin is a practical solution if you want to create more overview or space on your hard drive or SSD. If you accidentally delete the content you still need, in many cases you can simply retrieve it. The fixed volume of the recycle bin prevents you from wasting more and more space on the data carrier with your old files. A tip: You can also bypass the recycle bin directly by pressing the "Shift" key when deleting a file.

Duplicates take up space and make the overview difficult

If you want to free up space on the disk by deleting files, you should be concerned about any remaining copies. In everyday work on the PC, the files are often saved in different versions in different folders - especially with private photos. With office formats, the loss of space can usually be neglected; when working with pieces of music, photos and videos, the amounts of data are often huge.

The best way to find duplicates is to use a specialized tool such as Anti-Twin. It recognizes duplicate files not only by their name, but also by their content, and can even compare images based on their pixels. If you wish, it can hide the duplicate versions in the wastepaper basket.

EnlargeEliminate traces: Shadow Explorer scans the System Restore backups.

Additional copies are often in backup sets. You should keep this in mind if you want to delete files securely and permanently, as described below. Note that Windows also backs up files itself. For this purpose, it has the file version history available in the system control under "System and Security", which is, however, deactivated by default. Windows 10 also brings the Windows 7 backup tool with "Backup and Restore". And thirdly there is the system restore, accessible in the control panel via "restore". Use the Freeware tool Shadow Explorer to check which files and versions are contained in the program's backups.

Tip:Samsung presents inexpensive 4 terabyte SSD

Remove file references, delete tracks and data from the PC

However, Windows still stores references to files in several places, even if the data has already been deleted. Although the content can no longer be reconstructed in this way, file names such as “application.docx” are sometimes meaningful. For example, Explorer shows the 20 most recently opened files by default, and the same applies to Word and other programs. The PC also saves your last searches for files, folders or computers and stores this information in the registry.

EnlargeCcleaner includes the "Hard Disk Wiper" function to overwrite free space.

The NTFS file system used by Windows, however, also stores file information on the hard disk. The Master File Table (MFT) is a database that records all files and folders including their attributes. For example, Windows knows from the MFT which files are write-protected. You cannot reach the MFT itself with Windows, it is located in a protected area of ​​the hard disk. However, forensic scientists have the option to access it. If you want to discard a data carrier and safely remove all the information it contains beforehand, you should completely overwrite it, including the operating system. Reformatting or partitioning is usually not enough.

To overwrite, remove the hard drive and insert it into a second computer. There you can then overwrite them using the software. For this purpose, several tool packages have a function that fills the free areas of a data carrier with zeros. In Ccleaner, for example, you can find it under “Tools -> Hard Disk Wiper”. You can accept the default settings there, simply overwriting them is sufficient. The Secure Eraser tool, which was specially designed for secure erasure actions, is also suitable.

Alternatively, you can encrypt the entire disk, for example with the one included in Windows Bitlocker . The program's encryption algorithm is so strong that you no longer need to worry about the security of your data. You also have a back door in case you want to access the content later.

Differences between hard drives and SSDs

If you want to use the described Ccleaner function on SSDs, a warning appears stating that the disk can wear out prematurely through secure erasing.

EnlargeSecure Eraser is specially designed to securely erase confidential files.