Remove all the tiles from the dropped ceiling grid. Start at one end of the room and push the tiles up and turn them. Next, slide them through the grid vertically.
Disengage all the short pieces of ceiling grid from the longer pieces that are hung from the ceiling. The ceiling grids have tabs at the ends that connect together and are disengaged by lifting up and pulling them apart.
Unfasten the wires that may secure the longer pieces of the ceiling grid. Use a pair of pliers to help untwist the wire. Remove the fasteners from the ceiling to which the wires were attached. Remove the longer pieces once they are freed from the suspension wires. Unhook them from the grid around the perimeter of the room.
Unscrew the screws that fasten the ceiling grid on the top of the wall around the perimeter of the room. Use an electric drill with a driver bit installed to remove all the screws and remove the perimeter ceiling grid.