I just changed my first light fixture, so I'm a beginner. I took down 2 lights in an old bathroom, and only want to replace one. However, it is not working. The two original lights came on when I flipped the switch, so I am guessing it is on a parallel ciruit, and the one that I am not replacing needs to be closed.
two options here.
1. Put wire nuts on the ends of the wires. Put a blank cover plate on the old box and leave it. You can't bury the old box in the wall with live wires in it.
2. If the abandoned box only has the one cable that was feeding the fixture you can disconnect and cut of the cable at the other end. Push it out of the box so it can not be used again. Then you can remove the the abandoned box and plaster over the hole. Once the wires are dead you can abandon them inside the wall.