@Jan10198
If there is no active reservation (anymore), then you have to leave.
The 30 days notice is part of the cancellation policy, so if cancelled or shortened you still have to pay for 30 nights after check-out date (Or less if remaining nights in reservation are less then 30)
But a host (if willing to do so !) can overrule this policy by changing the reservation and amend price in change form to another deal you both are happy with.
https://www.airbnb.com/help/article/1361/how-do-changes-and-cancellations-work-for-longterm-reservat...