|It depends, obviously, upon the make and model. But, generally, you just need to logon with the current password and then you will have the option to change or (sometimes) remove it. It's better to set a new password that you can remember rather than removing the password, else anyone can mess about with your computer.|
Of course this relies upon you knowing the current supervisor passord. But that's the whole point of passwords, isn't it? They are there to stop unauthorised people from messing with equipment.