The linked article lists 10 different ways to demolish a hard drive. Unfortunately, several of the methods don’t actually destroy the data, but they do incapacitate the drive and necessitate the use of special equipment to read what is left. For those that do wipe the data, item #3 (using a grinder) is probably the simplest, and item #10 (Thermite) is definitely the most satisfying. Also, I’m not sure that any magnet, no matter how powerful, is able to completely wipe a disk. Back in my military days, the only approved method for disposing of classified hard drives was to physically break the platters into pieces.