Trim/Break
Trim (B) or split a sketch curve.
Trim
Remove one or more entities of a sketch curve.
- 
                On the Sketch ribbon, select the Trim tool.

 - 
                Do one of the following:
                
- Select the entity you want to remove.
 - Click-and-drag to draw a free-form line through the entities you want to remove.
 
 - Right-click and mouse through the check mark to exit, or double-right-click.
 
Break
Divide an entity of a sketch curve at a selected point.