If it plugs in, I'm afraid of it.
Oooo...okay then, unplug it and run and hide behind the sofa. If nothing untoward happens in, say, 4 hours, approach it slowly, holding a cushion over each ear. Poke it cautiously with a stick. If it doesn't explode, turn it over and look for two slidy-clippy things on the back or bottom.
These will most likely be on the battery, which will seem to be contiguous with the plastic molding. It will be something like 1.5" X 6-8" long.
One clip will probably show an open padlock and the other...something else, like 'Release'. Undo the lock one, and hold the other one against its spring while tearing at the battery join-line with your fingernails.
It would be wise to assess accurately, the possible trajectory of the battery as it flies out. Do not aim it at open fireplaces, or playful dogs.