As you have noted, you are going to need to do an erase config. If you try to retain an existing FI by itself, you have alerts for HA failure, and vif down links. You can get rid of some of the alerts by removing all vnics from service profiles that will be related to the removed FI. You will also likely have discovery and service profile association failures going forward, as the discovery and association process will always expect and try to validate a dual path configuration, unless the FIs are setup in single mode after erase config.
Kirk...
