In order to mark a Single unit as Out of Service, first we need to select the unit and the dates which it will be out, just like when we create a new reservation. Then in the 'Selection' panel on the right, we will need to choose 'Out of Service'.
Then in the Selection panel, edit and/or confirm the details of the Out of Service, then select the 'Mark Out of Service' button.
To mark a block of units Out of Service, First we need to toggle group selection from the Occupancy Map.
Then we will select the dates for each unit that we wish to block and choose to mark them Out of Service.