I've fubared two laptops and two desktops since Christmas, all machines that had gone seriously adrift and had obsolete operating systems.
I take out the hard drive, open it up, extract the rotating disk(s), and get a couple of Mole wrenches on them. Usually they shatter into extremely sharp, glass like shards. One of them just got more and more bent and ended up looking like a Pringle. Some people take gas torches to them.
BTW, it's well worth getting a set of micro Torx drivers so you can have a look inside a HD. The internals are things of beauty.