Doorbells run off a low voltage transformer. You'll often find it in the basement or somewhere near your main panel. Small silver thing about the size of you hand with house wiring on one side and usually two screws on the other.

So if we find that and remove it, it's ok to remove the box from the wall where the chime was, and patch over it, even though there's still a wire back there?

Excellent, thank you!

"You can abandon the wiring inside the wall."

Only if you disconnect the other end of the wire.

You cannot leave a live wire with one end open in the wall.

I said after it was disconnected from the transformer... brick

Department of redundancy department.

Just wanted to make sure it did not get omitted along the line.

There are enough ways to create problems with seemingly innocent errors.