@Brenda834 if the guest is a no-show and does not cancel, there is not necessarily anything you need to do. You will be paid, regardless.
However, it is true that third-party bookings are against Airbnb terms of service (unless it is specifically booked as a "work" trip by an authorized booker). So if the guest still wants to arrive, and you're not comfortable with it, you can call Airbnb and explain this.
If they try to get a refund due to "extenuating circumstances" that would not have affected the booking user I am not sure what position Airbnb would take.
In your shoes I would probably leave it alone unless/until you get a cancellation or someone other than the booking user wants to check in, at which point I would call Airbnb.
AirBnB number:
United States and Canada | +1-415-800-5959 +1-855-424-7262 (toll-free) |
For Superhosts (they will verify you):
North America: +1-647-945-9627 +1.888.326.5753