This tip is for Windows: 7 , 8.1
Most Windows users know that when you delete a file on a PC, it isn't truly gone and can still be recovered. Cipher isn't just a tool to overwrite deleted data it can also be used to encrypt data, which is not what we want in this case.
To use Cipher we have to use the windows Command Prompt and type: cipher /w:C
What this tells Windows to do is to start the Cipher program. The '/w' switch says to remove any data from the available unused disk space, and C tells Windows to carry out this action on the C:\ drive.
If your data is on a different drive such as a partition labeled D:\ simply substitute C for the correct drive letter. For most people, however, C will be the right choice.
Now, just sit back and wait for Windows to do its magic. This is one of those tasks you should run when you're not using your PC. Windows will also advise you to close as many running programs as possible to help the machine do a better job of clearing up your hard drive.
