@Alejandro85
ok your initial comments were directed to the OP?

To clear the CMOS you need to open the case and break the seals I mentioned. If the penalty in breaking seals means nothing then any protection other than encryption doesn't exist. You don't need to clear the password since you have physical access to the OS HDD/SSD. In this case it's easier to break seals than smash your way into a locked cabinet. In my original comment I was talking about a situation were you want to give physical access to the PC but control any fiddling outside of the user account.