To remove a point from a room outline, go to
Ribbon: DM Electrical->Buildings and Rooms-> 
Remove Wall Point
Pulldown Menu: DM Electrical->Building Definition->Remove Wall Point
You will be prompted to draw a crossing box around the room point to remove.
First crossing point around room vertex to remove:
You will then be prompted to specify the opposite corner of the crossing box.
Second crossing point:
The point on the room outline that is surrounded by the box will be removed.