I'm a bit surprised by someone who's familiar with an anarchist theory to be this naive about this stuff.
Today in Rojava (society in Syria based in part on anarchist principles) they are replacing the police with alternative institutions.
You can read more about it here: http://hawzhin.press/2020/06/01/how-to-abolish-the-police-le...
So instead of looking at alternative societies in Syria, how about looking at European countries and the way they are policing? Or Canada?