DeleteOnClick is a very simple-to-use program that securely deletes (wipes)
files so that they cannot be undeleted or recovered. Implemented as a Windows
Explorer extension so you just need to right-click on the files then choose
'Securely Delete' to wipe the files. DeleteOnClick completely deletes files
in one click and the data becomes unrecoverable, and also has the option to
wipe free disk space. (in System Utilities)