Remove IP Address from a Group via CLI command

Perhaps I'm misunderstanding you because I don't think there is an "exclude" command where I'm talking about, but if you mean an address group (config firewall addrgrp), the command to add members to the group is "append member <address name>" and the command to remove members from the group is "unselect member <address name>"

If this is the only reference to that address, then you should be able to switch config modes to config firewall address and then "delete <address name>"