Darshan, if you look at the official notification available at http://164.100.133.71/keawebentry456/cet2020/ugcet_secondround_noteenglish.pdf, you can modify your choices for Round 2 extended round. You are given the provision to add/modify or delete your existing options. And once the seats have been allotted and declared, you can use the option entry according to your interest based on the seat alotted. Please read our page for the dates and other information regarding the process: https://engineering.careers360.com/articles/kcet-seat-allotment . But to just answer your question, you can remove a college and a new college to the College list.