Obligatory “asking for a friend”. But no, like, if enemies of your state were possibly going to overrun a data center you rent a spot at but you still have some time, what’s the quickest way to, remotely, absolutely ruin any of the data on the disks? I can remember seeing old IBM "Death"Stars with the magnetic medium stripped clean. Don’t necessarily need that blatant a result, but say you didn’t have enough time to know if a basic dd /dev/{zero,random,urandom} /dev/mraid0 could run long enough to overwrite everything even just once, let alone a few times.
Alternatively, is there a file system which is purpose built for this sort of thing, where you send the array some sort of panic code – and I’m not considering drive encryption with a hardware or software key, whereas even if they were in place they are external to the disks themselves and thus at risk from external factors, rather than there being some command I can send to, well, if not crash the heads, then otherwise completely unravel the data structure in an irretrievable way with just one or two commands?
No password to gain if you stored it on paper. Get creative for your poor man’s switch. If you are already recycling paper without a care for longevity, the acid will quickly plump the indentation from your writing pressure and diplace ink and “graphite.” Great for the enviornment and ridding you of your pharmacy papers. Not so great for your sanity because it becomes a hobby.