On a aluminum clad door try to peel it back enough to get a putty knife or flat bar or something in there to help separate, if it's a PITA then in the shed pile it goes for me anyway. On windows usually they come apart pretty easy but if it's stubborn I will use a rubber mallet and tap on one of the mitered ends that is sticking past the glass, to help lift it up and away from the glass.
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