[plussed_reader]

From your description it sounds like when your child signed in with the student account, one of the Ok's they hit for GoGuardian put your device on the schools managed account(cps.edu).

If you're powerwashing and it's automatically pulling cps.edu managed policies as soon as it gets online then the school district IT needs to release your device, and then powerwash it and setup again without the cps.edu policies.

Be aware if you want your child to do any official testing or use their student accounts on your personal device the district may require this arrangement.

[iso1631]

Sorry, are you saying it's impossible to completely wipe/factory-reset a chromebook that's been adopted by an MDM?

[plussed_reader]

It is non-trivial to release hardware where the serial number is showing as mated to a managed domain.

If you're power washing and as soon as it connects online it gets cps.edu remote policies you're gonna need district IT to release the serial from management.