A little short on needed information but assuming the dish is in a ceramic tile installation the thing to do is to first remove all the caulk and grout that surrounds the dish. Then the dish must be broken out of its nest. This can be hazardous and you should wear gloves and safety glasses to perform the surgery. Once the dish is out there will probably be some remaining adhesive to also scrape away.
The next problem may be to find a replacement that will fit the old hole.