Revit Architecture
Revit MEP
(Room Separation Line). 
Room & Area panel
Room drop-down
(Room Separation Line) 
Room & Area panel
Room drop-down
(Room Separation Line If the space already contains a room, the room boundaries adjust to the new room separation lines. If the space does not yet contain a room, you can add one. (See Creating a Room.) You can also do the following: