Mark areas with studs or fixtures with tape and work carefully around them, working toward the sensitive spots. If you don’t have a stud finder, go around the room carefully knocking on the wall. Hollow sounding spots should be unobstructed drywall, but harder knocking spots will have studs and possibly piping throughout. Use caution in those areas, slowing working in that direction.
Use a utility knife to score the seam between moldings and drywall. The seam is typically filled with paint, caulk, or some combination of adhesive. If you want to reuse the molding, score the drywall edge of the seams to help fracture the wall where the molding and drywall surface will split.
Drywall screws can sometimes be removed with a Philips-head screwdriver, but depending on the condition of the wall, this may be more hassle than it’s worth. Look at the screws and the condition of the drywall itself. If they’re easy to remove, go ahead and remove them. It’ll mean less elbow grease down the road. If the drywall is wet, or if the screws are mangled, rusted, or otherwise difficult to remove, go ahead and start prying the drywall loose as if they were simply nailed in.
For unsoiled drywall, use a pry bar to begin prying the bottom of the panel away from these studs, allowing removal of the entire sheet. Pushing the short end of the flat bar up under the bottom of the panel allows for using the long end as a lever, making the initial prying easy.
Basically, what you want to do is open up some space to grab hold of the drywall and pull it loose. It’s not rocket-science: knock some holes in at the side and give yourself something to hang onto.
If the water-damage extends to the upper panel, the same action will usually cleanly separate the wall from the ceiling.
