easy unlocked 2017 only way need go to removery mode open terminal resetpassword
or
if Mdm locked go to recovery mode then disk Utility delete File then put in usb boost Macos dont turn On wifi prepinstalled completely when done turn On wifi if u see remote management pop up screen
open terminal
copy n paste
sudo rm /var/db/ConfigurationProfiles/Settings/.cloudConfigHasActivationRecord
sudo rm /var/db/ConfigurationProfiles/Settings/.cloudConfigRecordFound
sudo touch /var/db/ConfigurationProfiles/Settings/.cloudConfigProfileInstalled
sudo touch /var/db/ConfigurationProfiles/Settings/.cloudConfigRecordNotFound
done remote management disappear