If you want to delete them and make them inaccessible by anyway, you can use HardWipe.
The interface of the program is quite simple, clean and effective. The left column features basic actions such as eliminate files and folders, delete disks and purge free space, while in the rest of the window we can see all necessary stuff to do it.
You can control what you do until that exact moment you click OK, because, from then on, that information you have decided to delete will be inaccessible by any way.
Hardwipe can be very useful for those users who don't want to have their files exposed to other users, even if they decide to recover deleted files. Total protection for your privacy.