It is sometimes possible to remove glue from a casino chip. It depends on the glue and the chip. If the glue is bonded into the surface of the chip, it is best to leave it alone. Some glues are water soluable and if the chip can stand being in water without being damaged, that would be a good first start. If the glue has become rigid or brittle over time, it might just lift off with some help. You have to be extremely careful not to damage the chip, but you could try lifting with a very sharp edge, like an X-ACTO knife. I would avoid trying to remove the glue, if you are not certain that you will not damage the chip. Any solvent that would dissolve the glue, would also most likely damage the chip. You could test on a current issue chip and return then return the chip to the casino. The glue may have discolored the chip and after the glue is removed, you will have a funny looking chip. Be careful out there.