5 nuts (13mm head) to be removed from the trunk (2 at each side under the taillights and one in the middle). After these nuts are removed, the bumper can be slide off to the rear (the sides are slide over a bumper guidance and the front of the bumper at the rear wheel well, needs to be hooked out of the wheel well.
After the bumper is removed, you can unscrew three phillips screws at each side of the bumper cover and start releasing all the bumpercover-clips from the inside while pulling at the outside...
good luck & greetingz,
with a minor 600+k