Get 1/4 nylon rope and two cans of silicone spray lube.
Spray the rubber seal on inside liberally and liberally coat the rope.
Fold one of the top corners and put the rope in the rubber seal all the way round the window.
Use a 5-6 long piece of 2"x2" wood and push the window out at back vertical edge while pulling the rope to fold over the rubber seal to allow window to go out.
Once the back edge seal is outside metal edge then go forward along top edge and then down front edge.
You will need a second person before you get too far to be sure the glass doesn't fall out and break.
Use the 2x2 to push outward with not too great force to ease the rubber seal past edge.
Once the second side is started the removal usually gets much easier pretty quickly.
Install by setting the seal over the bottom edge with rope already in seal on the other three sides.
Use silicone spray liberally, lubrication is your friend in this job on removal and installation. Pull the rope inside to get the rubber seal edge to go over the metal edge.
Have assistant on outside pushing in with a 2x2 gently in the area you are working with rope.
Go to a automotive paint and supply store and get a plastic trim tool. I have heard them referred to as "bone tools" . It is 1 inch wide by 1/8 inch thick 6 inch long with one end tapered with edge sharpened on both sides. It is used to pop off mouldings and trim but it is great at helping the rubber over metal edge without harming paint or moulding like a metal tool might.