Hello aspirant

You can leave your bams seat in karnataka . Bit you won't get refund of fees .

For pursuing law again you have to start from class xii. You can pursue law course on the basis of class xii , you will have to appear for entrance exam CLAT .

Eligibility for appearing clat is to have passed class xii with minimum 45% marks from any reputed university.

There is three years LLB and  five years LLB .

For details you may visit the link given below

https://news.careers360.com/three-year-llb-course-integrated-five-year-law-degree-compared-colleges-curriculum-legal-jobs