If you are an F-1 student, you must request a new I-20 within 10 days of changing your major.
Change your major in UAccess:
Submit the Change of Major e-form to request an updated I-20. Normal processing time is 10 business days.
If you are a J-1 student, you are not eligible for a change of major. Meet with an international student advisor to discuss your specific situation further.