Yes, It is possible.
Note: Undo checkout is possible only before night audit.
Reason: After Night audit, we locked all data for previous date and that can not be changed, also by performing night audit, you will move to next day, so can not make changes in previous working date
Please follow the below screenshot to perform undo checkout.
Go to Departure list.
Search for the guest you checked out >>> select the transaction >>> click on undo checkout button.