If an administrator password is set and then forgotten, it cannot be overridden or removed.
You must replace the system board.
Power on Password Override (Bypassing an Unknown Power-on Password)
When a power-on password is set, POST does not complete until you enter the password. If you forget the power-on password, you can regain access to the server through either of the following methods:
For jumper location see System Board Locations 8660 (5500) / 8661 (5500-M10) / 8662 (5500-M20)
You do not need to move the jumper back to the default position after the password is overridden.
Changing the position of this jumper does not affect the administrator password check if an administrator password is set.