Mold in utility closet - how bad does it look?
From the photos the mold really is not that bad and there are several house hold chemicals that can kill it. Every one usually knows about bleach diluted with water. Another is hydrogen peroxide. There are products that can be purchased and sprayed on like mold be gone. I would spray it with one of the above solutions prior to removing the water heater and once it is out really clean it well.