Remove the existing light bulbs. Be careful as they may be hot and stubborn ones can break off in the socket base. Every light is different, your steps for removal may vary. Usually wall lights are secured with two or more knurled or decorative nuts. There may also be small screws on the sides of the light holding it to the mounting plate. Once the light is separated from the base, check all wires for voltage. If all is safe, remove one wire nut at a time, separate the wires and screw the wire nut back on the wall side. Remove any screws holding the light base to the wall.