You can restore a divided space by removing space separation lines. 
-  Open a plan view that contains the spaces being combined. 
- Activate zones and spaces visibility. You activate zones visibility only if the space that you are combining was added to a zone.  
- If the space that you are combining was added to a zone, remove the zone. 
- Determine which of the spaces correctly specifies the heating and cooling requirements for the combined space, and remove any of the other spaces in the area being combined. Note: You must remove a space when combining areas that contain spaces. If not, a warning will inform you that multiple spaces are in the same enclosed region.  
-  Remove the space separation lines. The areas combine into one larger area, and the space boundaries adjust to include the entire combined area.