Thanks for the info & photo…that helps a lot!
This is about the easiest situation possible (easiest computer to remove the HD from). All you need to do is disconnect the data & power cables from the HD…unscrew the HD mounting plate (should be 1 screw)…and remove the HD mounting plate from the HD (should be 2 or 4 screws).
As far as the hard drive itself. If the computer is still operational…you could do a secure erase of the HD (need to boot the computer from a compatible OS install disk).
If the computer is not operational...or you no longer have OS install disks to boot the computer from…or you don't have a 2nd computer to attach this HD to in order to secure erase it. Then this makes things more difficult (depending how sensitive the stuff is on the HD). Worst case scenario…you can open the hard drives case…and break/smash the hard drive platters.
Warning: If you decide to smash the HD platters. Depending on the platter material it can be VERY brittle (usually laptop HD's)…and can shatter like glass (sharp pieces). Or the platters may be metal. Then you can just bend & scratch them up so they are unreadable.
Here's an article on how to "destroy" an old hard drive:
http://www.wikihow.com/Destroy-a-Hard-Drive
As you can see in the article. The "physical destruction" method is probably the best way. Get out that screwdriver & hammer!
- Nick