You set up your session as a 4-Pane session. You get in only to realize that you are only going to use two or three panes. No need to change the session. You can resize the panes and push the new layout to all your attendees.
1. While in the session, use the resize handles to resize or hide the individual panes as needed.
2. Go to the Global Attendee Options and select Apply Layout.
3. The layout takes affect on your screen and is pushed to all attendees.