There is no process per se for Free exit. For example, if you have been allotted a seat and your joining is on or before November 10th, if you do not report to the College on or before November 10th, it will be considered as Free Exit. You will not be penalised and you can participate in the Round 2 of All India Counselling. But you have to fill in fresh choices again. Please read the FAQs available at: https://mcc.nic.in/UGCounselling/Documents/FAQMCCUG2019.pdf