How do i permanently delete files?

Simple File Shredder

Delete a file from your hard drive and it isn't really gone. Using the right tools you could get them back. If you need to make sure a file is deleted in such a way that it can't be got back then you need a program to overwrite it.

Simple File Shredder does exactly that, overwriting the file with random bytes to ensure that even with a recovery program the contents are worthless. A log is produced to show what's been deleted. The program can also be used to shred free space on a drive to ensure that any previously deleted files are destroyed. This is particularly useful if you are disposing of an old PC and want to make sure there's no personal data left on it.

You can find this file shredder at http://www.scar5.com/