Talk to your guidance counselor. Your counselor can lay out the options that your school has for students who want to test out of general education credits like math, English and foreign language. If you already possess skills in an area where a test is offered then you can request to take the test to see if you really need to take the class or not.
Take the test. If you pass the test then you have in essence proved that you don't need to take that credit and it will be added on to your transcript. You may have to pay a fee for the test, but this varies by school.
Continue taking these tests until you've passed all the ones you can. This way you have eliminated the maximum number of credits, and now you can concentrate on the classes you haven't taken on information you don't already know.