The rear and front Dino windows are formidable pieces of material with complex curves that are expensive and delicate. Originals are NLA and I've heard horror stories about repros possibly not having the same dimensions, so removal must be done without inflicting damage. When painting there are techniques to avoid removing the glass but many folks prefer to remove them. Here is how I removed the glass in my 1973 246 GTS #05702.
First, I decided that I would have to replace the rubber seals and I did not try to save them. Trying to save them seemed like it might cause too much flexing of the glass than I was comfortable with. The seals are expensive but readily available, so the seals were deemed expendable.
Prep the area by affixing a suction clamp on the center of the glass. This will give you a safety hold to grip the glass when it comes free. Also wear leather gloves around the edge of the glass to prevent cuts.
Woods makes a great 6 inch suction cup that I've seen glass installers use and I have the same cup on my Manfrotto car camera mount. It looks a bit odd with the tripod head but it is one of the best suction cups around. Paid for itself in this application alone http://www.filmtools.com/gripper-302...era-mount.html
Starting at one corner's end, gently separate the chrome from the rubber with a soft prying tool. The glass should not be used as a prying surface and the glass should not be moved or pressured if you're doing this step correctly. You only want to separate teh chrome from the rubber.
Go slowly with the goal of not deforming the chrome. When you have a small section raised, then string two lines through and behind the chrome. One line will be your pull for the top and the other goes along the bottom.
Gently work the lines in parallel along the top and bottom channels, doing a little at a time.