If you've mistakenly selected the wrong college or program on your application, the first step is to immediately contact the admissions office of the college. Explain the error politely and clearly, indicating the correct college or program you intended to choose.

Many colleges have a correction window or a specific process for handling such situations, especially before decisions are released. You can also check the college's website or FAQs for information on how to make changes or if there's a specific form to fill out.

I hope it is helpful for you.