[ORD C#] How to remove a TemplateDrop from Corridor?

SoftWare Version: ORD update7

Operating System: Windows10

Detail:

I want to Delete a TemplateDrop from a Corridor,but i can't find any function in .net SDK.

And i have tried to get the Element by TemplateDrop and use DeleteFromModel() function:  TemplateDrop.Element.DeleteFromModel(). But i find that can only delete a part of the TemplateDrop,some elments belong to that TemplateDrop still remain in the DgnModel.

So ,do someone know how to delete a TemplateDrop from Corridor?