Hii Mohit!
The quickest way to reach into the way for becoming a paracommando is via NDA entrance examination. And the eligibility criteria for NDA in terms of qualification states that the candidate must have passed class 12th or equivalent exam from a recognised Board of education froma my subject stream, that too, when you apply for Army. For Navy and Air force you need to have Physics and Maths as compulsory subjects. So, apply for Army in NDA. After completing the degree in NDA, you will be sent to IMA where you can volunteer for PARA during the last term.

So, having commerce stream is not a problem.

Hope this helps.
Good luck!