Question: If I wanted to completely and securely wipe a hard drive, could I simply write all ones or zeroes (or even just random zeroes and ones) over the entire disk to clean it? It’d probably take forever, but is my theory correct?
Answer: That should suffice. There is a theory that you need to do this multiple times because of variations in tracking, however the threat countered by this seems largely theoretical.
You may find it easier to use a drill or a very large hammer.