As others have said you can't sell an ABnB business because the reputation is based on the host not the property. However if you're selling a property with future bookings, this is the best workaround that I can see:
1. Add the new owner as a co-host so that they can manage future bookings (or you can if you prefer).
2. Change the bank details to theirs so that they receive the payout
3. Block all unbooked dates in your listing
4. Have them create a new listing in their sole name and block the dates that are already booked in your listing to avoid double booking.
6. Optionally , maybe insist that you're a co-host in their listing until completion of all bookings in yours to ensure they don't double book and leave your guests out in the cold)
5. When all bookings are complete in your listing, delete it.
Be aware that as a co-host they can manage blocking and unblociking dates so keep an eye on your calendar to ensure the new owner doesn't try to take bookings based on your listing and your reputation.
Finally, as always, communicate with your guests! They may receive messages from someone they don't recognise. Tell them you're doing this because you don't want to cancel their booking, you will oversee the account and they should contact you if they have any concerns. They can also cancel their booking if they are uncomfortable with this situation and you will refund all the fees that you receive (based on your cancellation policy). You may wish to also refund the ABnB fees that they would lose in this scenario since you're making thousands from the sale and the few hundred that this will cost you will maintain your reputation if you intend to continue using the account.
As far as I can see this doesn't contravene any ABnB policy, it maintains your reputation, doesn't cancel any guests and the new owner gets the benefit of the income which is a value you can include in the sale.