@Amy1621 There are two ways to do this:
1. Advise guest to cancel their booking directly through their Airbnb account. The remainder of the stay is immediately terminated, and the terms of your cancellation policy are upheld.
or:
2. Open the reservation through your account, select "Change Booking," and change the date of checkout. Here, you can manually enter an amount to refund, should you wish to do so. This initiates a request that only goes through if the guest confirms it.
The guest is not automatically entitled to any refund beyond what your chosen cancellation policy supplies just because they want to leave early, so you can stand your ground on this matter if you don't feel there's a legitimate reason for your payout to be reduced. However, if the reason they want to leave early is that the property is not as advertised or the listed amenities are not functioning, they can escalate by complaining to Airbnb, which may grant them a bigger refund than you're willing to offer.
For that reason, I would say that contrary to Collen's advice, the situation with the worst probable outcome for you would be asking your guest to "contact Airbnb." Unless you and your guests have reached a point of irreconcilable conflict, this is a situation that you're fully capable of resolving without the involvement of Airbnb's customer support.
