I've not removed the rear one (yet) but have taken off the front. basically just start at the edges and work towards the middle ....
I had to remove the inner wing plastic covers, and both headlights, and just kept un-doing bolts and screws until it was loose.
The headlights needed a bit of help to come free as besides a couple of bolts, there is a plastic push in fitting on the back of each unit.
From what I've seen under the rear of the car, the back bumper seems to be held on in the same way, so will probably have to remove
the rear inner arches to get at some of the fixings.
Good luck !