You can use any clear solvent to dissolve the moose antler glue. WD-40 works great! Use it full strength. __% will dissolve the glue within a few minutes. Then you can just wipe off the solvent with a dry rag. You can also just unscrew the antlers and take them off the skull. This is what many deer hunters do. It is probably illegal to use any kind of solvent on a mounted deer head though, so check your rules.
