Start by placing the charger face down on a rubber mat or a surface that will help it not slip/move around.

Then use a plastic pry tool, or anything that has a very thin edge, to go around the rubber ring and reveal the screws. If you do it carefully with a very thin tool, you will leave no marks on the rubber ring.

Use a small screwdriver bit to remove the 3 screws. If I remember correctly they are T5 bits.