Drop it -- but recognize that you have a problem.
If you're serious about the possible majors you mentioned, you're going to have to take essentially the same calculus course as a college freshman. And you're going to need to truly understand the material because you will be using it in later courses.
Is it possible that you are struggling now because of a shaky foundation in precalculus last year? If it is, and if you can afford it, you might want to consider getting a math tutor -- to review precal with you, not to help you through calculus. Or, if you're going to have a free period, would your school let you sit in on a precal class? Or could you take a precal class at a community college next summer?
The idea here is for you to be able to hit the ground running the next time you take calculus.
I should also add that if you're in trouble this early in BC calculus, it's definitely a signal that something is wrong. The first few months of BC calculus cover differential calculus, which many students consider to be easier than both precal and the integral calculus that comes up later in the year.