If you want to dispose-off of your hard disk or just deliberately wish to erase the data from the hard drive then simple delete or Shift Delete is not enough as the data can still be recovered again.
There are occasions when we want to permanently delete our secret or confidential information from the disk so that it can’t be recovered back. The best way to do this is to use a third party tool which can delete the data and fill the hard disk with random data. One such tool is called Roadkil’s Disk Wipe that securely erases the contents of a disk replacing it with random data or leaving the drive completely blank.
Although one pass of the operation is enough, you can still perform several passes to ensure that the data is totally unrecoverable. The tool is small and can wipe off the data easily. The program works on hard and floppy disks as well as USB/Flash drives.