No login
From MoodleDocs
Location: Settings link in Administration > Users >Authentication > Manage authentication
An account may be disabled by setting the authentication method to "No login". The account email may not be re-used to create another account. This essentially is a way to bar a particular user account from using Moodle for the duration that the account is assigned to this authentication type.
To change a user to this authentication type, go into his or her profile. Click the Show Advanced button, and select No login as the authentication method. Then click update profile.
