Well, let's see. First, they cancel all your remaining ADR's. Then they freeze your room charge and credit card. Then they start a methodical hunt for you. When you are found, they put you on It's a Small World and stop the ride while you are in the "white" section. They leave you there until you beg for mercy.
I'm kidding. Unless it's an ADR with a guarantee on your credit card, it's no worries. You can stop by any resturant or guest services and they will cancel teh ADR for you, you don't need to go to that restaurant. It is polite to cancel though, as someone else without an ADR might want to get in for a meal and be able to if they know in advance that you aren't coming. If it is a meal with a credit card guarantee, the cancellation policy will be exp,lained at the time of booking.
Anne