Cut the tyre off, then get a pair of long nose pliers and roll the tyre off, clean the wheel with a ******* file

...that's the way I prefer, but you can try boiling it, soaking in solvent or glue removing solution

(the type of file will probably be swear filtered out but it's the roughest file in the set and the name I used is the generic name for it - just hit quote and you'll see the name)