Convertible rear window removal ?

So I ordered a new rear window. The one thats on there, the the vinyl is tearing on the lower half under the window. My question, how does this thing come off? I know about the zipper inside, but I can see the other half of the zipper attachment is somehow tucked under one of the roof metal frames. How do I get that portion removed? Do I have to totally disassemble the whole top just to get the back window off?

Ideas?

Here is a pic of the area I'm referring towards. I want to know how the rear window attachment on the top side of the zipper is attached to that metal brace. Not the snap, but tthe material that is tucked under the metal bar. The zipper doesnt come fully undone.. the rest is still attached at the very end.

Thanks, thats all I needed to know. I have a feeling the color isn't going to match because the material has faded a lot. I wanted to get a new top, but that's allmost $400. So I'll just put up with this for now. It's enough to stop water from making a mess in the back.