Hii aspirant..

In the counselling process if you have saved your option of of willingness to upgrade your college then you cannot change it.

But still if you have time left in your hand for changing your your decision as you have not saved the option to upgrade you can retain the college allotted to you in second round.

I hope the deadline for or saving your choice of a upgradation is still left so that you can change the option and get the seat back again  in 3rd round that was allotted to you in second round.

Hope it helps. 

Best of luck