This is a picture from a house in Westchester NY that we did mold removal on. We had to remove the lower 48” of sheetrock in order to get all of the mold that was growing. This did two things, first it removed the mold on the sheetrock completely, remember even dead mold is an allergen, and secondly it allowed us access to the interior of the walls so we could treat the studs. When sheetrock becomes damaged and moldy from a flood or a leak it is best to remove and replace with green board which is what is used in bathrooms. Green board or some of the other bathroom safe mold resistant sheetrocks are the way to go in damp basements or if you are remodeling a bathroom or kitchen. They will save you a lot of trouble the next time there is a flood or a leak.
As you can see in the picture the studs have been sprayed with Calbrite anti-microbial solution and they are being hand wiped clean. The mold needs to be killed and then removed. Out of frame there is a plastic wall that we erected and an air-scrubber to prevent contamination into other parts of the house. The air-scrubber filters the mold spores out of the air and also collects all of the loose dust. The barrier and air-scrubber was left running for another 48hours after we left in order to polish the air.