Once you've removed the lower facia there are two screws at the back of the head unit frame
Very hard to get at but with the right stumby driver you can get there. Alternatively, you can use a small socket(8mm I think) as the screw has a socket head.
Once done, push the rear of the head unit frame/facia best you can. Can get tricky. The fastener near the hazard button is the one that I found hardest to open. I found that opening the side nearest the steering wheel was quite easy. Then teased it open from there. It is tricky so patience goes a long way.
Good luck