How do I delete the files on my computer permanently? Undelete programs are still able to recover them. How can I delete the files that are not displayed, but undelete programs can recover them? I tried writing new files onto my computer. I tried reinstalling with the original restore computer to factory settings cd. Yet, my old files with personal information are still recoverable using undelete programs. What are some solutions to permanently delete these hidden files? I want to delete these files forever so they cannot be recovered.