Once the Check-out time passes on a reservation, it goes into the archived status and users no longer have access to edit.
Now Hostfully allows users to adjust information about Direct Bookings.
Common items needing editing are:
Taxes and fees
Any difference in amounts (additional payments: refunds/credits/extra payments..) once the reservation is archived should require a manual payment request or refund.
This feature only applies for Direct Reservations, it is not allowed to modify archived reservations from OTAs (Airbnb, Booking.com, VRBO...)