How do I take the case of my iPhone off?

[nick h]

I put an invisble shield protector on the front and back of my iPhone. Then I put another case on it that just covered the back. I thoght the invisible shield glue was dry but when I put it om my iPhone started overheating all the time now I want to take the case back off but I can't because it seems like the invisble shield had glued it on. Any help on how to take it off