Sometimes there is also a section of the lower panel that is held in place by the upper window frame and the screen. I would take that out and see if there are any additional fasteners under the screen frame. The inner trim and the outer window are supposed to be 2 separate pieces. There may be clips that are holding the trim ring to the vista view, much like the clips that hold the inner door trim to the door frame. There are also rivets that sometimes hold the sheet to the door frame. The trim around the door it a T shaped molding that should be able to be gently pried out. Try not to lose any clips, or bend it. It is soft aluminum. To reinstall use a rubber mallet.
WBCCI #5501 AIR # 49
1978 Argosy 28 foot Motorhome
Wise men talk because they have something to say; fools, because they have to say something. -- Plato