After creating a floor, you can change its profile to modify its boundaries. 
-  In a plan view, double-click the floor, or select the floor and click Modify | Floors tab
Mode panel
 Edit Boundary. 
  Watch the tooltip and the status bar to be sure you select the floor, not another element. If desired, you can use a filter to select the floor. See 
	 
Selecting Elements Using a Filter. 
	 
Note: If you are not able to select the floor, try Enabling 
		
Select Elements by Face and try selecting the floor again.
	 
 
   
 
 
- Use sketching tools to change the boundaries of the floor. 
 
- Click 
  
 Finish Edit Mode.