Two options with hard drives.
Target practice
Dismantle them. The platters make great coasters. The super powerful magnets can hold a cast iron skillet to the refrigerator.
I take 'em all apart for the magnets. We're approaching a day where everything in common use will be solid state and the magnets will be exhausted for the most part.
There will probably always be platters in enterprise devices since the data doesn't degrade over time like it can in an SSD. I've fired up drives that hadn't been powered on in 20 years and they still worked. Good luck finding an MFM/RLL interface these days though. IDE is getting harder as well.