Hello dear, for admission in delhi university, candidates  must register themselves to the online UG admission portal available on the main website, www.du.ac.in using your personal email IDs .

Upon the declaration of CBSE results, the online portal will re-open and then you will be allowed to enter the marks that you have secured. And then after few days University will release at least 5 cut-offs. Applicants shall be allowed to take admission in whatever course or college they desire, provided you meet the cut-off. ( Special cut-off shall also be declared only for those who could not or did not take admission in the initial 5 cut-offs).

So in DU I have not seen that any college require prior registration. It's you how have to choose the college or course after the declaration of cut-off .

I hope you got the answer . Good luck!!