They can’t. But they can come out of the DA play school season then go back to the DA. I emailed us soccer and this was the response I got.
It’s up to the club to accept them back.
In their manual:
(1) Players who receive consideration or financial aid to attend a private high
school based on their participation with the soccer team are eligible
(2) Although clubs are not limited to a specific number of waivers, the number is
naturally self-limiting to field a full team throughout the Academy season.
(3) Players registered with a Development DA Club will not be allowed to re-enter
the program during the same season after participation
So if a player decides not to play in the DA so they can play in high school (as long as they meet those requirements) its at the clubs discretion whether or not they will accept them back. Seems fair to me. Unless you are on scholarship to a private school for soccer or your DA team doesn't field a team that season, you cannot simply just play school ball and request to come back. This is my understanding.