To remove mine, I first had to pull off part of the weatherstripping (its not glued, no biggie).
Then pull up the side plastics that go from the floor up to the rear window. Remove them completly.
Then you have exposed the sides of the rear panel, grab the sides and pull the rear of the panel towards the rear of the car to loosen it. Then you can grab the whole panel and lift/rotate it towards the front of the car, popping the clips as you go. Its then loose and you can remove it carefully.