I need to change the stainless moulding/seal assembly on my 69 Roadrunner.

I thought I could just pull it off, but that didn't work.
It is a hardtop, and the one on it has been pried on to the point that it is a mess.
So then I figured better just to pull the glass out and change it out of the car.
So I tried to remove the glass, and it looks like it is held in with some sort of plastic tree, but I have been massaging it for a while, trying to get it to loosen up, but it does not seem to be moving? I want to be careful not to break the glass, so any tips are greatly appreciated! ? ?