Ohh No, Don't panic better try calling PMSSS and mail the ACITE with your reason and your candidate ID. Also, put the grievance from your portal and request them to again change the status from the backend. I am sure someone who will be an admin can solve your problem easily.
The administrator can undo your action but do it early without any delay so that the 2nd round list should not get release. Mail them and tell them what you actually wanted to do i.e either freeze the college or float option.