DO NOT heat it. You could melt the plastic guides which would just change to a different problem.

As suggested above, try a thin blade of some sort between the glass and the guide. A flexible thin putty knife would be what I would start with.

Since we are talking about exploding tempered glass my opinion is that it breaks when its time is up. Yes, sometimes contact with a hard object can trigger it, but there are many examples of where that does not trigger it to break.

I have had two glasses break just holding them in my hands. In both instances I was removing them from a game only to clear the lockbar receiver to have them explode with no contact.

When its time is up, its time is up.