Turn off the power to the light box at the circuit breaker. Flip the light switch on and off twice to make sure the power is off.
Lift the plastic panels that cover the lightbulbs out of the box housing. Tilt them down and pull them out of the housing. If there is a metal or plastic grid in the light box housing, pull this down as well.
Unscrew the old lightbulbs in the light box. They may be traditional lamps or long, thin tubes. Either way, unscrew them completely from the socket and discard them.
Unscrew the metal or plastic light box housing from the ceiling. Hold the fixture in place with one hand as you do so, to support the weight. Lower the housing far enough to give you access to the wiring.
Remove any wire caps capping the connections. Disconnect the fixture wires from the house wires. Pull the fixture completely away from the ceiling.