No authentication
If you do not need authentication or authorization at all (for example, you're only running npm Enterprise inside your firewalled, private network), you can configure npm Enterprise to accept whatever credentials users log in with, and allow everyone access to everything.
In order to do so, set the following settings in /etc/npme/service.json:
args.--authentication-method and args.--authorization-method to "fake" args.--session-handler to "redis" Make sure to regenerate scripts as described in Customizing server configuration.
The npm CLI will still require that you log in in order to publish packages, but you can just log in with bogus credentials (although the username you input will be inserted into the package document - for example in the maintainers field).