[LeRoySmith]

My advice would be physically destroy the drive.

In my former life I managed data centers for a big insurance company, part of that work was to see that the old servers were destroyed and recycled. There was a pretty robust process to ensure we didn't destroy a drive accidentally, well one got through and made it's way into the press that bends the disc so it couldn't be read. The systems department realized their error in sending it to us and and asked for it back. I took it myself to their head, it was very bent up from the press. They took that drive to a magician and he retreaved the data. I would have bet anything that was impossible but they did it.

From that point on our presses were outfitted with a spike that went all the way through the drive so it have a big hole poked through it in addition to being bent up. A couple of years later I bought a big grinder and we sent them out as little pieces.

Obviously most places don't have those kind of resources but never say never.