Hi Aspirant,

Yes you can cancel the seat.Once you dont report for the seat the seat gets automatically cancelled.However it is your extended round and you cannot get seat after this round is over.You can wait for MOP UP rounds but that doesn,t always happens.So i would recommend you that you dont leave the seat for the college.

You may again give the exam next year in case you feel you dont get your aspired college.

Hope it helps!!