Plastic or mylar? Doesn’t matter either way. Heat’em up in the oven and make the labels peel themselves off. Might need a little scotch brite to get the rest of the adhesive off. Or hold em with an oven mit and take a propane torch to ‘em. Just don’t get it too hot because you’ll stress the glass and it may explode.I think y'all missed the post about the labels being plastic and difficult to remove...