Preventing new account creation
If you don't want new accounts to be created when users log in with an OAuth 2 service: 1. Go to 'Manage authentication' in Site administration and tick the box 'Prevent account creation when authenticating' (authpreventaccountcreation). 2. Click the 'Save changes' button. Source: https://docs.moodle.org/38/en/OAuth_2_authentication