You can quickly clear (mass unselect) your Spaces, Resources, or Services within an event.
To get started, go to the "ITEMS" tab within your event, as shown below. Then select the Spaces, Resources or Services tab.
At the bottom left corner, you will see a gold button to quickly clear your desired items from the event. Here is an example of the button that is displayed to "Clear Spaces" (see attached).
Once you have removed your items, be sure to select any other desired items, then re-submit your event for approval.