When given the choice between continuing an activity like orchestra in which a student is already heavily invested, which they enjoy, versus adding one more AP class, the answer is almost always to continue with the activity.
So, in my opinion, @builtdifferent, you should not drop orchestra. The benefits of orchestra for you, in all facets of your life, including college admissions, are far higher than the benefits of taking one more AP.
In any case, you are in 9th grade, and college is somewhere in the future, so keep your focus on being your best you in high school. Your plan for high school should be that, when you graduate high school in three and a half years, you will be proud of what you accomplished, regardless of the college which you attend.
Take care and good luck!
PS. My kid took no APs in either freshman or sophomore years and is attending a really good college.