To exit from JoSAA counselling, you can simply stop participating in further rounds. If you have not accepted any seat, you don’t need to take any action. Your seat will not be allotted in the next rounds.

If you have accepted a seat and want to quit, you cannot cancel it through the JoSAA portal directly. Just don’t report to the allotted institute or don’t pay the admission fee. Your seat will automatically be cancelled. But remember, you won’t get the seat acceptance fee refund unless rules allow it.