The Erase Tool is used for cutting strokes in the Sketch Window.
Which also can be used to remove or shorten parta of a stroke.

To Cut a Stroke

The Erase Tool is used to Cut a Stroke in the Sketch Window.
First choose the Erase Tool, select a Stroke in the Sketch Window and Click anywhere along the stroke to create a cut.
This new cut now creates 2 seperate strokes which can individually be moved or altered.