You can prevent users from signing up to your business, and only add users selectively.

You might do this if you only want to give access to employees or members.

Disabling sign-ups applies across an environment, and cannot be controlled per application or per organization.

1. Go to Settings > Environment > Details.
2. Switch off the Allow users to sign up option.

You can then import users, add them manually, or add them via the API.