Sure there are programs out there that repeatedly write over your disk to ensure your data is destroyed. Those programs are for pansies. You could run one of those programs and then drill holes in your hard drive. That option is strictly for wimps and those working for the government. So by now you are probably asking "When a real man wants to destroy his data in a way that it stays dead what does he do?". Good question, the answer; he rips the platters out of the drive and melts them into slag!
Ok, so at this point I should probably say that I would be, by the above definition, somewhere between a pansie and a wimp. However I know some weird people. One of whom, upon being invited over to my house for one of my first experimental aluminium melts, brought some aluminium alloy hard drive platters; what you see here is the result.
Here you can see the culprit platters. Which aside from being bent, I believe have also already been exposed to very high gaussivity magnetic fields.
Here we are loading the platters into the crucible of my first charcoal foundry. (Details of the foundry are available here ).
Since you were probably wondering yes it was raining when we did this, and that was not a good idea. As this was one of my early melting attempts we didnít melt the platters on the first try. It took two more tries until I could reliably turn them into molten metal. Still on this first attempt we ended up fusing the platters together turning expensive gigabits of data into one cheap ass paper weight.
Oh and while I am very confident that no one can read data from a platter that had been turned into molten metal it is not an approved data destruction method by any agency I know of. Oh and while I am giving disclaimers playing with molten metal is inherently dangerous if so if your going to do anything like this be careful and be safe.