Dell MFP 1815dn - How do I perform factory reset?

I recently acquired a Dell MFP 1815dn printer and apparently the previous owner had locked it somehow. The only Menus available are Copy, Scan and Fax even though the manual says there are many more -- including the menus where you configure the device.

Does anyone know how to perform a Factory Reset on a 1815dn so I can gain control of this device for use on my network?