They were foolish if they thought “wiping the server” was really a solution.
But, if I wanted to go down that road, I would remove the HDD, smash it a few times with a hammer, stick it in a bag of bad garbage, drive 30 miles to a random 7-11, and throw the bag in a dumpster.
It would never be found and/or examined closely.
Not a real solution, since the Russians, the Chinese and the NSA would have copies, but still seems better than “wiping it with a cloth”.
Just drill through the case and the platters usually shatter. No recovering anything if the media is disintegrated.