See in most of the colleges, you cancel your admission, if you want to go for an upgrade course. But before, applying you should check the terms and conditions very well. Some science colleges, don't allow to leave course and have set some penalty fees for leaving the course. So before, admission you should ask the college officials well regarding the terms of leaving the course and then only take admission. If you take admission in Affiliated colleges under state universities, then in most colleges you will be able to leave the course without any doubt.

For BSc Colleges in India consider the link below:

https://medicine.careers360.com/colleges/list-of-bsc-colleges-in-india

I hope this helps. Wish you a great eve!