Hi Praveen,

If you go by this excerpt taken from BCI rules you will get answer of your follow up question
"Three Year Law Degree Course: An applicant who has graduated in any discipline of knowledge from a University established by an Act of Parliament or by a State legislature or an equivalent national institution recognized as a Deemed to be University or foreign University recognized as equivalent to the status of an Indian University by an authority competent to declare equivalence, may apply for a three years’ degree program in law leading to conferment of LL.B. degree on successful completion of the regular program conducted by a University whose degre."

I hope it helps!

In order to take admission for three years law programme in Delhi University, You need to appear DULLB Entrance Exam conducted by Delhi University. The registration starts in the month of between May & June. You can check the complete information about with the given below link.

https://law.careers360.com/exams/du-llb

Good Luck!