You might want to take a look at this
http://www.dell.com/support/manuals/us/en/19/poweredge-r220/PER220OMPublication/Disabling-a-forgotten-password?guid=GUID-65F178F4-958A-4FD8-96AF-CCC26AD15B17&lang=en-us
And this:
http://www.dell.com/support/manuals/us/en/19/poweredge-r220/PER220OMPublication/System-board-jumper-settings?guid=GUID-60BD6540-5BFA-4A17-8F78-78A5B089F6C9&lang=en-us