How to remove management off of a chromebook

do you guys know a way to remove management off of a chromebook? I have had my Samsung Chromebook 3 for at least 2 years and i wanted to do a powerwash. So I did that and... I accidently signed into my school account. Now my chromebook is my school's chromebook. But I can still sign in with my regular account. But I can't turn on Linux or be in dev mode. I use Linux for steam and a virtual machine. Can someone help me remove management?