Before you give away a computer, you should make sure that your most private, sensitive files are irretrievable. You don’t want them to fall into the wrong hands.
But that’s not all. You should also return the hard drive to its factory condition, so that the new owner can set it up as they choose.
Let’s discuss both topics.
Securely wipe sensitive files
If a file contains information that you’d rather not fall into criminal hands (or government hands), merely deleting that file isn’t sufficient–even if you empty the recycle bin. Deleted files can be restored with simple, free software.
Instead, you should wipe those files–overwriting them with new, meaningless data. As a general rule, the more times the file’s former location on the drive surface is overwritten, the more secure the wipe.
Should you wipe the entire hard drive? That’s a popular solution, but not one I recommend. Doing so may make it impossible to reinstall Windows–not a good idea unless you’re giving your PC to a Linux user.
I suggest using the free and open source program Eraser. It integrates into Windows Explorer, so you can simply right-click a sensitive file or folder and select Eraser>Erase or Eraser>Erase on Restart.
But that’s not enough. Pieces of your sensitive files may be sitting elsewhere on your hard drive, in places that are officially blank. To fix that, you should wipe the unused space on your hard drive. In Windows Explorer, right-click your C: drive (or whatever drive contained your data files) and select Eraser>Erase Unused Space.
Be patient. That could take a while.
Your PC’s new owner deserves a fresh Windows installation–even if it’s of an out-date-date version.
Your PC came with some sort of recovery tool intended to give the operating system a fresh start. It might be a bootable disc, but more likely it’s a hidden partition on the hard drive.
Check your manual, even if you have to find it online, to see how you can restore Windows on your PC. If the tool asks you how destructive the restoration should be, pick the most destructive option.
If, when it’s done, there’s a Windows.old folder on the hard drive, delete it.