After doing some Google searching, it seems it is not obvious to a lot of people how to remove the HDD password on a Toshiba laptop, specifically in my case the Toshiba M400 Tablet PC. The only option in the BIOS setup screen appears to be to reset the password with no apparent way to remove it. As it turns out the solution is incredibly simple:

  1. Open the BIOS setup menu
  2. Go down to the HDD password
  3. Type your current HDD password and press Enter
  4. Now press Enter twice at the requests for the new password and confirm new password
  5. Press END and Y

That's it. Password cleared.