Only allow admins to invite new users
Note: This feature can only be controlled by organization administrators.
By default, any user in your Zulip organization can invite new users. You can change your organization's settings to only allow administrators to invite new users.
Select the Users need an invitation to join and Only admins can invite new users checkboxes under the Joining the organization section.
If this option is enabled, only administrators in your organization can send email invitations to new users.
Click on the Save changes button to save any changes you made to your organization settings.