In an attempt to send my scores to colleges, I also sent the Math 1 Subject test on which I got a 580. I do NOT want them to see it. Is there anything I can do to cancel sending the scores?
If your request to send the Math I score is still pending, call College Board customer service at (866)-630-9305. They may allow you to cancel it, but you should also be prepared for them to deny your request. On the College Board website, it says "If you contact us to request a service, once we receive that request, it cannot be canceled." They may be unable to do anything about the situation at this point.
If that is the case, don't freak out too much. I assume you also took other subject tests where you got better scores, so it's likely that colleges will pay attention to those and largely ignore the Math I score. Even if you just sent the SAT I and Math I, they will be more interested in your Math SAT I score than your Math I subject test score. I would only be concerned if you're applying to extremely competitive schools where your qualifications are already marginal.