When admins create communities, they are required to set community privacy settings. There are two options to choose from:
Open: When a community is set to Open, it becomes accessible to the public. Anyone who wants to join can do so automatically without requiring admin approval. Open communities can have content that is publicly viewable and indexed by Google or other search engines.
Closed: When the community is closed, all prospective members will be required to send a request to join the community. They must be approved by admins to become members of the community.
Step 1: Click on Admin Panel.

Step 2: Click on Settings & Data at the bottom of the side menu and select Settings.

Step 3: On the Community Details tab, scroll down to the Community Privacy section to update your privacy settings.

Step 4: Click the Save Settings button to save the changes.
