Flange Frustration


I am having some frustration with a toilet flange. I have discovered the floor under the black tank is rotten. Unfortunately, I need to remove the toilet to get to the flange; remove the flange to get to the wet bath fiberglass; remove the fiberglass to get to the black tank; and remove the black tank to get to the rotten floor. The flange is meant to spin off but it is made out of cast iron and is rusted solid. It will be out by this weekend.