devs

Hi guys, I wondered if someone could help me..? I've got a DS-7604NI-E1 that I've just with no issues in a previous property. I've just gone to set this up in a new house with one new camera... The NVR seems to still list the 4 old cameras that were used on it and it does not detect the new one that is plugged into port 1. I have tried to delete the old cams from the list but it returns the error "does not support delete operation" Trust this is because its looking for the old cams that are nolonger attached. What can I do to resolve? Is there a way to default the NVR back to factory? Any help would be appreciated.