Hi, according to the website of the nsit delhi centralized counselling is done for admission in Nsit, Dtu,Iiit-D and according to the merit college and branch is provided. The merit is based on 12th marks and Jee mains rank 40% 12th marks and 60% jee mains rank. These are the mandatory eligibility for admission. So,i don't think without appearing in jee mains admission is possible. You can give it a try by contacting them contact is given in the official website. Good luck