1994 Buick Roadmaster Owner's Manual - Page 254

Unscrew the wingnut. From outside the vehicle, carefully pullthe taillight assembly away from the body. Press the bulb housing release lever and turn housing the 1/4 turn counter-clockwise (to the to remove it. left) To remove the bulb, push it and rotateit in counterclockwise (to the left). Reverse all the steps to reassemble the taillight housing.