Addtional director

As per the Companies Act , the Addtional Director is appointed until the conclusion of Next Annual general meeting 

but in my query is that company appoint Addtional director As on F.Y 11-12 but Forget to resign tham and my mistake they also show them for F.Y 12-13 Annual Return (20B, 23AC,23ACA.)

So please tell me the process to resign tham 

should i file DIR-12 from back date or any other Alternative ??????