How should I tell CalPoly I dropped a class?

I’m a high school senior. I’ve applied to CalPoly’s Art & Design department with a concentration in Graphic Design. Starting at the end of January, I’ve dropped AP CompSci and have become a TA. On the CalPoly website, the deadline to change the application for Art & Design majors is January 1st.

How should I contact admissions and tell them I changed my high school transcript? Should I just email the admissions department? Surely I’m allowed to drop a class at this time of the year and tell them somehow…
Thanks,
Rachel

Email admissions.