You can apply or remove the start/end shapes on rules by R&D panel, or by scripting.

For scripting, use the StartId and FinishId properties of the ElementProp object. As parameter, enter a valid terminator id, or 0 - to remove the terminator from the rule.

Dim elem As ElementProp = Page.SelElement()

elem.StartId=3

elem.FinishId=2