You should first remove the bigger trim, the one to the left of your pictures, by removing first the two U-shaped rings (one is visible on your picture), and the 3 screws. on the bottom covered by quite loose plastic caps, ad then pull it as straight as possible away from the window. It is clipped.
Once done you will see how you can remove the Right Hand Side upper plastic trim, by removing a screw, and the pulling it out from rear to front as straight as possible:
View attachment 7852597
I hope I remembered it well enough without forgetting something crucial, but other people have documented it in the past too! If you are patient in your search, you will find better explanations I guess.
[EDITED] Here you have the complete rear right trim dismounted.
View attachment 7852599
