Can I permanently erase the hard disks before selling my laptops?

Q  I want to sell two old laptops, but am concerned that the contents of their hard disks will be read by future owners. Is there any software that will completely delete the contents of a hard disk?

I am aware that digital ‘footprints’ can be left, but I would like to ensure I have done all I can to clear them.
Chris Thompson

A  Simply formatting a hard disk will not completely erase the contents: with a little technical know-how, some of all of the data may be recoverable. What’s needed is a ‘secure-deletion’ tool that overwrites the hard disk’s data, making it impossible to recover.

A great option for doing this is a free tool called Darik’s Boot and Nuke – download it from the DBAN website. Burn the file to a CD and then use this to launch the laptop. Just follow the simple on-screen instructions to begin the secure-deletion process.

A tool such as Boot and Nuke is extremely effective and will erase everything from the hard disk. This is the only way to be certain that all personal data on the hard disk has been securely wiped.

However, this method will also erase the operating system and any applications that may be installed – and you or your prospective purchaser may not want this.

As an alternative, consider using Eraser – another free secure-deletion program, but one that can be used in a more selective fashion. You can download it from Eraser's website by clicking here. There are a couple of ways to use Eraser – either wipe all free space on the hard disk, or securely erase specific files and folders.

If using the first method, use Windows Explorer to delete all your personal files and folders then choose New Task from Eraser’s Erase Schedule menu.

On the Task tab, choose the Run manually radio button, click the Add button, select the Unused disk space radio button, make sure the correct drive is selected (usually C:), tick the ‘Erase cluster tips’ box and click OK and then OK again.

Now right-click the new task in the Erase Schedule list, choose Run Now and Eraser will do the job – it could take hours, though.

The second method is quicker and easier but traces of earlier deleted files may be left on the hard disk, so it’s significantly less secure. However, if you want to use this method, with Eraser installed, right-click on a file or folder in Windows Explorer, point to Eraser then click Erase.