How do I remove the rear window in a 68?

My friend and I are standing here trying to remove the rear window in my 1968 mustang. I took all the pieces off the outside of the window but now I am stumped. Do I just puch the window out from the inside? Or remove this nasty rotten gasket around the window.

--Josh
 
The easiest way to do it is to get a razor knife and cut the gasket around the perimeter on ther outside of the window .The window will just come right out. Then just clean off the remaining gasket and junk.
Bob