If it is an older top the glass is in the same way it is in the older rear windows of a truck. The rubber gasket holds it in place.
From the inside, take a thin hard plastic putty knife, pry thr gasket from the outside egde while putting slight pressure pushing the glass to the outside, work your way around until it pops out,
to reinatall the glass, get a small diameter rope or thick string, put vasoline on the rope and gasket, then put the gasket on the glass,put the rope/string in the groove that will go aroung the actual opening, set one edge in the opening of the top,,, and slowly pull the rope as someone holds the glass in place. As ya pull the rope, it brings the gasket edge into the opening.