I know your car has a vent window. I don't remember, however, whether or not it has a track in the back for the glass.
At the bottom of the vent frame, there is a 7/16" or 1/2" bolt holding the bottom of the track in place. Remove the bolt, and pry the track forward, poping the glass free from the track.
If it has a back track, which I think it does, it might have a bolt(s) too. If it has bolts on the top and bottom, remove both bolts and pull the back track.
If you ONLY want to remove the glass, you don't have to do all of what is discussed above.
Have a Service Manual? The procedure outlined in there makes it a piece of cake. However, you'r going to have to pull both the inside and outside window felts off.
I take it you have the door panel and watershield off already.
Mark the postion of both the front and rear window stops and then remove them.
If you unbolt the rear window channel, pull it back (or better out) and then remove 2 small phillips head screws securing the metal window frame to the regulator arms, the glass is now free of the regulator. and can be pulled out the top of the door.
2012 Mustang Boss 302 #1918, Competition Orange. FGF replacement 2006 Mustang V6 Pony, Vista Blue. Factory ordered. 2019 BMW X3 (Titled to the wife, but I'm always driving it for her. So I'm claiming it) Old projects, gone but not forgotten: 1967 FB 400, original CA car. After 22 years of work, trashed by the guy who was supposed to paint it. I had to sell it. 1980 Turbo Trans Am 1970 Mustang fastback, 351C 4Bbl, auto 1988 Mustang GT, 5 speed 1983 F-150 4x4, built 302 1994 Chevy K2500 HD 4x4, 454 TBI