How to delete my hard drive safely? [duplicate]

Use DBAN.

Darik's Boot and Nuke ("DBAN") is a self-contained boot disk that securely wipes the hard disks of most computers. DBAN will automatically and completely delete the contents of any hard disk that it can detect, which makes it an appropriate utility for bulk or emergency data destruction.

If you want to make the drive unrecoverable, I think your best bet is to remove the platters and take a belt sander (or sand blaster) to them. By ripping off the magnetic coating, you'll insure that nothing can ever be recovered. Obviously, doing so makes the drive useless, but for maximum protection, you can't beat destroying the magnetic media.

Another approach would be to use a heat gun (or blow torch) and a putty knife to scrape the magnetic coating off. This is bad because who knows what the fumes will contain, but you won't have a load of who-knows-what dust around the workshop.

Another approach would be dropping the platters in an appropriate acid, but I'm not enough of a chemist to know which one would work best.

I don't think much of the drill method proposed by another poster - it only destroys part of the surface, making recovery of only some of the data impossible.

If your objective here is to remove any possibility of recovery EVER, then you really need to attack ALL of the magnetic media on the entire surface. Anything you can do that turns the magnetic media into particulate matter is going to be sufficient.

Of course, as far as we know, no one's ever recovered data from a drive after it's been over-written with zeros. So, it really just depends on how paranoid you are.

You can also check out File Shredder, a free Windows utility to delete files securely.