Deepika, the official webiste FAQs section states that a Candidate who belongs to OBC Category and wants to claim OBC-NCL benefits should have a certificate done after March 31st, 2020. And the certificate should state that the Candidate belongs to OBC-NCL and the Community is listed in the Central OBC List. But if you have uploaded State Certificate by mistake, you can make changes as long as you have not made the payment for the application form. Once you make the payment for the application form, you cannot make any changes to the application form. And the guidelines also mention that no candidate should register twice or fill in the application form twice. Now you haven't mentioned whether this is for UG Admission or PG admission. So we shall give you the helpdesk email ids for both sections. Please reach out to the appropriate help desk. If you are applying for Bachelor's courses, then you have to mail undergraduate2020@admissions.du.ac.in  and if it is Post Graduate courses, then you have to mail: pg2020@admission.du.ac.in