As a longtime armchair attorney who has closely read summaries of cases like this on Slashdot for well over the past decade (IANAL, BTW)...you could go the lawyer route but this basically amounts to your kid being a minor in school which means they don't have full legal rights, and the interpretation of 4A is likely up in the air here anyway. Constitutional rights don't necessarily apply at school or anywhere near sc…
The important part here is that the computer is not usable with their software and that you have no way to remove said software despite being the owner of the computer.