if the town is at or under 500 rating points you can destroy. I'd send a free hero with a very small army, like 20 archers/marksmen/swordsmen, and one scout. the attacking army is automatically sent home. A long time ago, I did this, and my troops were sent to their homes (a troop's home is the city that supports them). there were suggestions to change it to just send the entire group to the nearest city, but I do not know which one it is.