Hi @Kathleen441
You can not remove it because the booking is confirmed and the money is already with Airbnb.
You can, if you wish, send the money back to the client - but I would wait until after the booking is completed - if you send it now, and the guest cancel the booking in a few days, he will get the money twice.
Just as a FYI, you cannot add a service fee after a booking is confirmed as well. This is also because Airbnb assumes that the client agreed with the amount, and extra charges after that at not allowed