Create public, private, and unlisted Chatter groups to collaborate with your teams and work together on projects.
Follow the steps to create chatter group,
Step 1 : Click the Groups tab.
Step 2 : On the Groups page, click New Group, and enter a group name and description.
Step 3 : You can automatically archive the group by enabling the below option”Automatic Archiving”. Also you can avoid to archive
Step 4 : Select an access level for your group based on your requirement.
The chatter group has been successfully created you group.