If you are done with a group, you can retire it. You should retire a group which is no longer active (a completed project, a client engagement which has ended), but whose information you may still like to search or review.
The option to retire a group is available only to organization owners and group admins, and is found at the bottom of the group settings screen.
Groups that you wish to remove entirely can be deleted after they are retired. Deleted groups will have their messages retained for 30 days, in case you need to restore it.
Members who only belong to a retired group will not be able to log in. Members who only belong to a retired group do not count towards the organization billing.