Creating a Partial Flange Junction
The part shown below has partial flange junctions on the front and back corners:
 
        To create a partial flange:
- Select an edge or face that belongs to a junction. 
- Change the junction type to No Overlap, if necessary. 
- Change the Junction type parameter in the Sheet Metal section of the Properties panel to None. 
- Click  Pull in the Edit group on the Sheet Metal tab. Pull in the Edit group on the Sheet Metal tab.
- Select the outside edge of one wall of the junction. 
- Drag the yellow balls in to the points where you want the flange to end, as shown below.   
- Pull in the direction that is parallel with the adjacent wall, as shown below. 