You need to make up your mind! If you want to "physically" destroy, I recommend drilling three 1/4 inch holes through the drive and through the platters.
But if you want to destroy only the data to ensure no one can retrieve it, you need to "wipe" the data - which really does not wipe at all, it just overwrites every bit, byte and sector with a bunch of 1s and 0s, ensuring there is no "residual" magnetism from previous saves. But, in order to run wipe on the drive, it needs to be recognized by the computer.
Rather than putting it in an enclosure, I would install it in a computer as a secondary
boot) drive. Then run the wipe program. I prefer Eraser
. It uses the highly respected DBAN protocols, but with a GUI interface.
If the drive is not recognized, you have but two choices - trust the drive maker, or drill holes and buy a new drive.