Yes you can change college/course in the 2nd merit list by cancelling your admission under 1st merit list.

You can change the college/course by following this procedure:

Withdraw the previous admission:you have to withdraw the admission taken in any college under previous cutoff list.you need to download the cancellation form from the official website and fill it.

Cancellation fee payment:you have to pay the requisite admission cancellation/withdrawal fee.

Download the confirmation page:once you have withdrawn the admission,you can download the confirmation page.

Select new college and course: you can now select the new college and course by logging into the official website.

Document verification and payment of fees:the document verification process would be conducted at the time of admission.Once the document verification process done,you can claim the seats by paying the fees.