The only way to insure that information is completely destroyed is to destroy the disk that holds the information.
OIT Hardware Support provides data destruction services to insure complete destruction of data when retiring or surplusing old computers.
We can destroy data on almost anything you use for storage. We have a shredder for removable media such as CDs, DVDs, and floppies. For hard drives, we first ask that you erase the data on the drive with a software program. Then bring us the drive, or we'll remove it for you for a fee. We'll de-magnetize the drive, rendering it unreadable, and then destroy the drive in a machine which physically crushes it.
For more details about our data destruction service, including information about preparing your drive for destruction, see this KnowledgeBase article, or contact Adam Re by phone at 8-6037, or e-mail firstname.lastname@example.org.