Related Questions:
Is there a way to reinstate a group that was previously cancelled
How can I change a Group from lost?
Is it possible to move a group from canceled?
Answer:
Within Event Temple, a Groups status can be updated at anytime, as well as it's Booking if the Booking itself was also changed to lost.
To update only the Group Status:
From the Booking Summary
Click Edit next to the Group
Select the new status (as shown below)
Click Save
From within a Booking
Click on the current status in the top-right
Change the status
Click Save