Do I have to take science in high school to become a pilot?
There are no specific high school or college academic requirements specified for pilots in the U.S. Code of Federal Regulations.
However, basic knowledge in math and the physical sciences is important, and will greatly improve your understanding of subjects that are taught in ground school so that you can successfully pass required written and oral exams.
Furthermore, to be competitive as a professional pilot a college degree definitely helps, and you will likely need some minimum science credits both to get in, and to graduate.  Don't skimp on your education!