In the days of smartphones, Windows etc.. Seems a bit excessive, but for peace of mind, you can just spin the HDDs up (start a defrag, for example) and shake them hard.
It will not destroy the data, but you’ll not recover it without sending it to a lab specialising in data recovery. Scoring the platters doesn’t destroy data either, it damages the platter. Everything that isn’t scored still stores recoverable data.
A simple magnet will not destroy the data either, that’s a movie myth and referring to HDDs from the 70s/80s. While it is true that magnetic fields can destroy data, a simple magnet is nowhere near strong enough. There certainly are neodymium magnets that reach the required strength, but they’re big money and not an average household item. For reference, it needs a pull strength of around 450lbs to be able to wipe modern platters. A degausser (a tool used by the industry to wipe data) can cost tens of thousands of pounds.
If you just want to make data inaccessible for someone picking the HDD up, just smash it on the floor a few times. If someone goes to the length to scavenge the platters and reinstall it in a new casing and head (which is an extremely complicated/delicate process, requiring tens of thousands of pounds worth of tools and a cleanroom), then no effort bar having it professionally disposed of will stop them to get at least partial data.
The safest way bar sending it to a disposal facility is simply to overwrite it. Plenty of file shredders out there (file shredders don’t delete your data, they overwrite it with gibberish files, making it unrecoverable from HDDs). Takes quite a while though (dependant on the algorithm, anywhere from an hour to multiple days).
Generally, i was never able to care. All my old SSDs and HDDs got formatted, then thrown away. Technically the data is still recoverable after just a format (because you’re not deleting the files as such, you’re just deleting the reference to it, basically), but it already requires so much effort that only professionals can reasonably do that. These kinda people usually don’t go dumpster-diving for HDDs.
Prior: SEAT Ateca Xcellence Lux 1.5 TSI DSG MY19, VW Golf GTE PHEV DSG MY23
Current: Hyundai Ioniq 6 Ultimate
Next: we'll see what's available in 2028.