You definitely have some options on stocking once the grouper is gone. The Maroon and Wrasse may harass any new inhabitants, but you should be ok if you stay away from more wrasses or clowns. I don't know how big the 2 are currently, but generally adding fish bigger than them will prevent them from acting aggressive towards the new fish. If the wrasse and maroon are pretty big already then I would try to get new fish that are quite a bit smaller and not perceived as much of a threat. Rearranging your rock upon introduction of new fish will also be helpful.