‒ Sorry, you can't empty the garbage yet. A paper towel in here is currently in use by some object in your house.
‒ Which one?
‒ I dunno, it's your house. Just check each object.
‒ Check it for what?
‒ Whether it looks like it might have touched a paper towel at some point and then forgotten to let go.
‒ ...
‒ You can also Google to learn how to check which things are using which resources.
‒ You know, I'll just leave the towel there and try again tomorrow.

:D