The lower light housing uses two different types of body clips molded into the housing so it will required two different methods of removal.
First take a thin bladed standard screw driver and apply a layer of masking tape over the blade end, this will help protect the paint, insert the blade between the housing and bumper cover at the bucket end of the housing itself (where the light eliment would be) on the bottom edge of the opening and pry out slightly to disengage the bottom clip on that end. Use another taped screw driver to repeat the same process to the top side just above where you just did the other. Once those two clips have been released you will be able to pull that end out a little more but not too much. Now for the fun part, the two remaining clips are elongated requiring you to push the housing towards the center of the car. Once the housing stops within the slot then pull the opposite end of the housing out and away from the bumper cover. To replace the cover just perform this in reverse order. If your nervous about scratching the paint, outline the opening with masking tape.
Have fun