Hello Kuldeep, 

If you have scored 81% and you have reserved seats through SC Quota, you would surely be able to make it to Delhi University. You would have no problem, however, you may have to wait for cut offs to go down in order to get into colleges from North Campus.

I suggest you to first secure your seat in any college whose subject and college cut off matches your scores and once the cut-offs are low, you may get admission to your desired college and course.

Good luck!