Take down the panels from the ceiling. Push up one corner to lift each panel out of the grid. Turn the panel so it fits down through the opening.
Shut off the power to the room if your lighting is installed in the dropped ceiling. Disconnect the light fixtures to remove them. Cover the ends of the wires left in the ceiling with twist-on wire nuts.
Cut through the wires that hold the frame for the dropped ceiling. Remove the wires from the joists.
Remove the runners to take down the grid. Disconnect the bars, which are typically held together with slots and tabs at the ends of each piece.
Take down the perimeter track that's attached to the wall. Remove the screws that hold it in place, or pull out the nails with a hammer if the track is nailed to the wall.
Patch the holes left behind using spackle and a putty knife. Let the material dry before sanding it to make it smooth.