The defaulting procedure is in the manual, also in the FAQ section of Avaya's support site. Or, connect through the LAN port with the GUI, and it will be easy to wipe out the existing boxes and attendant settings.
Just swap the 4 port card for the 2 port, (don't leave them both in the voice mail, it's one or the other), and program the port extension numbers into Hunt Group 7 in the ACS, and you'll be fine.