If your guest has booked several nights and decides to check out before the last day of their stay for whatever reason, you'll most likely want to make their room available for sale again for the remaining dates.
Do not drag the booking onto the Calendar screen's shuffle row. This will not release the availability.
In most cases, we'd suggest clicking and left-dragging the end of the booking bar on the Calendar to reflect the actual nights stayed, or clicking into the booking record and editing the departure (Booking To) date from there.
You can amend the Total price figure for the room, or add any cancellation penalty extra to reflect the amount you are going to charge the guest on departure.
And finally, check them out.