@Jillian63
The guest can cancel if they want to but long-term bookings follow the long-term cancellation policy which is no refund for the next 30 days or if the remaining duration is less than 30 days, then no refund at all.
https://www.airbnb.com/home/cancellation_policies#long-term
https://www.airbnb.com/help/article/1361/how-do-changes-and-cancellations-work-for-long-term-reserva...
https://www.airbnb.com/help/article/43/what-happens-if-my-guest-cancels
https://www.airbnb.com/help/article/448/what-does-it-mean-to-enforce-or-waive-my-cancellation-policy
Whatever the GUEST decides to do, as a host, DO NOT CANCEL.
Do not accept or agree to a message you might get that says "The guest requests that YOU cancel" - agreeing/accepting this will also make it a "host" cancellation.
https://community.withairbnb.com/t5/Hosting/BEWARE-of-quot-Guest-requests-that-you-cancel-quot/m-p/4...
In order to open up your calendar, the guest will have to cancel and accept the fact that there will be no refund. IF the guest cancels, then you calender will open up for the remaining days so you will be able to accept new guests for the remaining dates.
(If it's what you want) you could approach the guest and say you will provide a partial refund based on no. of nights that are re-booked by new guests. This could encourage the guest to cancel without a refund for now, but you should also make it very clear about the amount you'd be willing to refund so for instance, say that for every night that is rebooked, you will refund X amount. Just a thought~
Good luck~!