I want to take the windshield out of my 68 charger. I have removed the trim. What is the next step? I was told that i needed to cut the gasket and then the windshield would pop out. Do I run the razor blade along the top surface of the windshield and cut the gasket like that?

That's how I have done it. Razor knife around the perimeter. Make sure you do not try to pry it out of position. If you cut the gasket completely it will come out fairly easy.

I cut the surface edge off and then created a hole in one corner to feed a steel fishing leader thru and had a friend help me "saw" around the glass. Then it was REAL easy to push right out!

The windshield gasket is actually reusalbe. It has a flap and groove that has to be "unlocked" to remove the windshield. With enough time, patience, and lubricant, the glass can be removed and the gasket reused. They can be tight if they've been in there for a while and it takes a lot of soapy water or silicone, and finesse to loosen them. Be gentle because like the others say any prying at all will crack the windhield.