How to erase sensitive files or delete files permanently
If you want to delete files permanently from your computer. What do you do ? Do you use shift + del? Well shift delete does not erase the file from your hard disk. It just removes the file from file table hence your OS can't find it. But the data is still there on the disk. The best method to remove sensitive data is to erase using eraser.
What is eraser?
Eraser is an advanced security tool (for Windows), which allows you to completely remove sensitive data from your hard drive by overwriting it several times with carefully selected patterns. Works with Windows 95, 98, ME, NT, 2000, XP, Windows 2003 Server and DOS.Eraser is Free software and its source code is released under GNU General Public License.
The patterns used for overwriting are based on Peter Gutmann's paper "Secure Deletion of Data from Magnetic and Solid-State Memory" and they are selected to effectively remove magnetic remnants from the hard drive.
Other methods include the one defined in the National Industrial Security Program Operating Manual of the US Department of Defence and overwriting with pseudorandom data. You can also define your own overwriting methods.