Delete Part
Drawing > Delete > Delete object 
> Dummy parts 
Delete 2-D dummy parts
Use this function to delete all parts below the active part that do not contain any graphical elements. The parts will be deleted immediately after activation of the function.
Drawing > Delete > Delete object > 2-D, in rectangle 
Delete 2-D elements in rectangle
If you draw the rectangle from the top to the bottom, all graphical elements lying completely or partly in the rectangle will be deleted.
If you draw the rectangle from the bottom to the top, only graphical elements lying completely in the rectangle will be deleted.
