@Natalie413
Per @Helen3 's advice, you will have to continue to badger Airbnb until they cancel the stay. Be prepared for a negative review/retaliation from the guest and difficulty getting Airbnb to remove it. Be sure to leave an honest review for this guest.
If you want some strategies on how to request removal of a negative review, you can send me a direct message, or just add to this thread.
Future Prevention
1. Do NOT accept last mintue bookings.
2. Change your lock to a smart lock so you can control it remotely and change the code if necessary in the future to prevent guests from re-entering. This also saves you the hassle of re-keying the lock and/or guests losing keys or copying your key.
3. Turn OFF Instant Book so you can vet your guests before accepting. What kind of reviews did these guest have?
4. What is your maximum stay setting? For listings where Owners occupy the same property, I suggest limiting stays to 7-14 days.