See Computer Science is a very math oriented field. Right from the first day you'll be dealing with complex problems of Calculus and Linear Algebra along with concepts of Probability and Statistics. So I would suggest you that before making a plunge in computer science, try to make your fundamentals in these mathematical areas strong, otherwise you'll not be able to cope us with the pressure.

If you think that you can manage learning math along with pursuing your BCA or B.Sc degree, then go for it. But if you don't think that you'll be able to manage maths along with your degree, then the only logical option is to take a drop and give the paper of maths.

I hope that the answer I gave will be able to help you to take an informed decision. All the best!