Echo cougarstrong. Find a nice corner or out of the way spot and keep the rabbit in the cage for a few days. Maybe put a piddle pad around it and the wall at first. Thy really prefer to find a place to relieve themselves and they'll go back every time so after. You can take them out but don't let them run around the place until they settle on that corner as where they do their business. After that, keep the cage door open when their free and they'll go back there on their own. Pull the tray and toss to clean, wipe down every other time.

Lots of water and timothy hay, supplement with pellets and veggies. Frozen water bottle if hot/overheated. Kids usually like given them an igloo to sleep in/sit on/chew. Some chew more them others, like they think the carpet is grass. Remember they are prey animals so don't like being high in the air or in the open without options to hide. Many like eating aster plants if you have any (beyond the usual suspects).

Hope some of that helps. If you change your mind, please don't dump it in the wild, they die/get eaten quick. Give it away or to a shelter.