Hello sachin, for changing your stream from B.com to BCA it depends on your college that does your college allow you to change. But generally you can't change your course from B.com to BCA because they are entirely different courses. B.Com is commerce course and BCA is a computer course. And if you really want to do BCA then you can quit from B.Com course and then join in first year BCA. I hope you got your answer

Good luck !!