I agree he has to get approval from the coach (who will get it from admissions…and they may or may not allow it). He can NOT drop the class until he has approval from the coach.
I’ve told this story before but D19 committed to a top LAC. Wanted to drop AP CS second semester and add another CS class that was at the SAME level as the AP class (but not called AP) at a rigorous ‘known’ HS. It was a huge ordeal, and for a time looked like they might not allow it. It was the coach’s first year, so they learned a lot throughout the process too. Admissions ultimately did allow the switch, but it took a month of back and forth, sending syllabi, reading materials and the like back and forth with the coach as the middleman. My D NEVER spoke with admissions.