at present change the course physics chemistry & computer science to physics chemistry Mathematics
Hey , be frank with your question. It is hard to understand what are you asking.
But, i would like to tell you that computer science is an optional subject for pcm students(physics, chemistry, maths). So, there is no meaning of changing course. But if you have choosen pcm or pcb, and want to change them. You can always ask college management to do so.