Accepted to Cal Poly but dropped a AP class in senior year

Hi,
My son was admitted to Cal Poly engineering for 2018. His high school is a 4 x 4 block system so he takes 4 classes and then 4 classes in the Fall and Winter terms. On his Cal Poly application he listed AP stats for 2nd term. He ended up dropping the class before he started it because he was doing 2 varsity sports and he didn’t need the class to graduate or meet CSU requirements (not required). In fact, his counselor told us he shouldn’t have taken the class in the first place…but we listed it it on his application since at the time he was going to take it. Dropping the class didn’t change his MCA score but we are afraid of telling Cal Poly admissions until he gets his final transcript. What do you think? If Cal Poly rescinds, he will go to Davis (his back up school), but his heart is at Cal Poly. What do you think we should do? tell them now or tell them when he has his final grades? I appreciate your input.

Tell them now. If they have an issue, they will tell him. But he cannot/should not assume they will not notice when the final transcript goes in - they will!! No college likes to get a surprise like that late in the game, so he needs to get in front of it. He will likely not have an issue.

How would he go to Davis now if he already turned them down and committed to Cal Poly?

Yes, would like the answer to the question that @VickiSoCal posted above??? Did he SIR to both schools?