Resignation as the treasurer of a co-operative society.

I am presently, a treasurer of a co-operative housing society in Mumbai consisting of 21 members only. I want to resign owing to differences with other society members. I am on this post for the past eight years. Nobody is willing to take responsibility. I have sent my resignation twice to the chairman but he adamantly doesn't accept my resignation as he knows there is no one to fill in the gap. He doesn't even acknowledge the second copy of my resignation letter. My question is, if the chairman keeps on rejecting my resignation letter and doesn't acknowledge it, can I send my resignation letter to the chairman via speed post with AD? Should I send it to the secretary too? Can I write in the resignation letter that I have already finished all work and nothing is pending as of now and whatever I have with me with respect to the society, I am submitting it to the secretary? Last but not the least, can I with immediate effect without getting my resignation accepted, cease to work as the treasurer of the society and am I needed to send a separate letter to the deputy registrar of co-operative societies informing him of my resignation? Should I send a letter to all the banks also where savings account of society is operated, informing them too about my resignation? Sorry for making this too long. Kindly advise point wise and oblige. Thank you in advance.