I have some extremely sensitive data on a computer, hard drive, and on a private server. I do not care about cost or method, as I have a lot of funds (though not unlimited) and I do not want to go through a third party data sanatization company. I also do not want to connect those things to internet because the time it is exposed will make it a target for mallard, Trojans, Spyware, etc. I need a wally that will completely destroy and delete the data. It should not be recoverable by any software or technology possible. I also would like a way that is more reliable and secure than physical destruction. That could work, if I hit it with nitroglycerin, throw it in acid, burn it, melt it, then spread the pieces around the world, but that would take a lot of time and I would like a quick way.
Assuming we are talking about a traditional spinning platter hard disk drive: unscrew the disk housing completely then score the surfaces of the platters as much as you want in both complete radial lines and also circles. Put them into a burning brazier when finished.
Of course you could do this instead of zeroing all the data but you can do the whole lot depending on how paranoid you are.
SSD? Remove memory chips from housing and blend.