Wipe Free Disk Space By One Command Cipher.exe (/w)

Cipher.exe (/w) command line tool

Whenever you create text files and encrypt them till such a time that the encryption process is completed, Windows will create a backup of the file, so that in case anything was to go wrong during the encryption process, the data would still be recoverable using this file. Once the encryption process is completed, the backup is deleted. But then again, this delete backup file can be recovered using data recovery software, until it is overwritten by other data.

Cipher.exe thus allows you to not only encrypt and decrypt data, but also to securely delete data. Thus, many use it todelete files permanently too.

PROCESS-

1. OPEN COMMAND PROMPT 
2. TYPE      Cipher /w:X   where X is the letter of the drive or partition you want to wipe.

Be patient—the process can take a long time if you have a lot of free space.