How do I undo the "enable lock & erase" on android device manager?
In your phone, go to the settings, then go to lock screen and security, tap on other security settings, in there you'll find Device administrators, tap on it, then you will find the option "Find My Device" you can turn it off or on.

This settings path may be OEM-specific; other devices may have slightly altered terminology, though Device Administrators is generally well-marked.