Yes, it is possible.
How to Access: In order to perform undo check-in operation please follow the below steps and video
But please note that it is possible only for the guest checked in via reservation, not for direct check-in guests.
User Privilege: eZee absolute configuration >> User >> Edit user >> Privileges >> Front Office >> Access to Allow Undo Check In.
Location: right-click on guest name >>> click on Undo check-in.
And this can be done before night audit only.
Another way is from Arrival List
Location: Front Office >> Arrival List >> Search >> Guest Checked in today >> Search >> Right-click on guest name >> Undo Check-in/Dayuse