So what do you do with an old bowling ball? A sphere of rubber or plastic with 3 holes drilled in it. You could use it as a planter. I have seen people paint them and use them for lawn ornaments. Cannonball? Boat Anchor? Pretty much a useless item unless you have dreams of one last 300 game before retiring it.
They don't sale at garage sales, auctions or flea markets. They are too large to be used in boccie tournaments. They make lousy cat toys (even with a little catnip sprinkled on it ). So what do you do?
Trash, Trash Trash! Two great ways to get rid of them. The first one is simple put them out at the curb. Your trash man will hate you for putting such a heavy item out but oh-well. Second, go out and bowl one last game with it and accidentally forget to take it home with you. The bowling proprietor just loves getting free bowling balls so make sure you go to a place where the chances of anyone recognizing you are zero. One exception wooden balls (not to be confused with brass). So if your balls are made of wood make sure you have someone check them out before put them into the trash.