Turn off the light switch that controls the chandelier, and then turn off the electrical power to that area at the breaker box. Let the lights on the chandelier cool before handling it.
Unscrew the screws that hold the canopy in place against the ceiling. Lower the canopy gently down the chain and rest it on the chandelier. Set the screws aside.
Remove the wire nut covers over the white and black wires. Unscrew the wires and disconnect them. Loosen the ground wire screw and disconnect the wire.
Turn the nipple in the mounting bracket to unscrew it. This will disconnect the chandelier from the ceiling, so have an assistant guide the chandelier to the floor if it is too heavy for you. Slide the canopy up the length of the chain, and then pull the nipple through the opening in the middle of the canopy to remove it completely.