It’s possible you want to delete files off flash memory and not be able to retrieve them back. Gone is gone – no recovery software would do the trick – permanent removal.
Well, if you can live without the DOD (Department of Defense) specification, then here is some free software to perform secure deleting. This program allows you to specify a directory (and optionally all subdirectories) in which all files should be deleted. When each file is deleted the contents of the file are filled with random data prior to deleting the file.
Let say you are a software programmer and signed an NDA for working on some code. After your project is done you want to permanently remove that code to honor the NDA agreement. This software is quick-n-easy to do just that.
The download site also provides the source code to get in there and make your own modifications if need be.
What I like about this utility is the option to specify how many times you would like to re-write the deleted files with bogus data. The DOD recommends at least 7 overwrites while a more stringent specification (Gutmann Method) recommends 35 times.