Disconnecting Airtel Broadband connection - process

Hi i am using the Airtel broadband connection from last one year or so but i am not satisfied with the services provided by them and that is the reason why i want to disconnect it. The other thing that i was willing to give it a chance but the speed was degrading consistently and also the downloading speed was not that so good. So i decided to break the connection but some how i am not able to do so and also don't know the exact procedure of doing it.