disabling power-on-password

there is a power-on-pass needed at boot-up. maybe this is related to the problem that we cannot power-off with button. maybe button is defective.

how can i get rid of this pass? i have any pass disabled in bios(its a compaq with its own bios)
but i cannot enter any pass. maybe i must enable first. but this is probably not the right way gettign rid of the login.