|The real question you should be asking is Why do you think you need to update the bios of this machine?|
The fact it has a Bios power-on password indicates it is a laptop and unless you are experiencing any issues with it there is no valid reason to touch the bios.
As to disabling the power-on password that is done by entering the bios, searching for the appropriate security setting and disabling it. Of course this presumes you know the password in the first place. Does the machine have any specific issues that are supposed to be resolved by updating the bios or are you trying to do so just because a newer bios is available?
Goin' Fishin' (Some day)