It depends on the glue used. Pick a solvent and give it a try. My usual progression for dissolving unknown glues is isopropyl alcohol (or denatured alcohol), naphtha, acetone, high heat, and lastly, methylene chloride. One of those chemicals will dissolve just about anything. Be careful with the last few on that list, as they can be quite dangerous. The high heat is good for epoxies like JB Weld. Though with glass, you have to be careful, and raise the temperature slowly so you don't crack it.