I would not recommend find -delete as it deletes files.
You can easily remove/change a HDD if it is an USB adapter for an M.2 drive. That is the most secure solution. If you want to be really secure you would need to take your computer offline and take the M.2 drive always with you.
Booting via USB3.0 does not work on all computers so you may need to boot via USB2.0. Precisely at the time when you have loaded the kernel you may however remove the drive physically from your USB2.0 plug and simply plug it into an USB3.0 slot.
Another solution I had for long with my desktop computer is to carry a SATA drive with me and have an external HDD dock. Of course you may also use an eSATA case for your HDD if you have an eSATA port.
Some hints on securing your computer can also be found at (see at the bottom):
Am 04.08.19 um 23:57 schrieb Ruslanas Gžibovskis: