It's more like a thumbwheel in there. You may be able to use a screwdriver, but a brake adjustment tool works real well. It's bent just the right way and you can get them at any auto parts store. I can't remember which way to turn it to back off the brakes, but once they are backed off it may take a bit of pounding to get the drum off. I had to tap mine with a heavy mallet before they loosened up.
