How to trim or cut Append flange in Pro structure v8i

Dear All,

           I have  created plate with Append flange, I want to cut or trim extra Append flange part (see attached snap).

I have tried every option to trim this Append flange plate but not able to cut this object. If any one know about that please guide me how to do.

I am working on Bentley pro structure v8i ss4  auto cad 2012.

Thanks in advance.


Shrinivas Jadhav