You are considered a member of an organization if you belong to at least one group within the organization.
Joining an organization
Public groups can be joined by clicking the Join the Conversation button at the top of the group page.
Private groups can only be joined by accepting an invitation via email, or by being directly added as a member by a group administrator or organization owner.
Leaving an organization
You can leave an organization by leaving all groups within an organization.
To leave a group, you will need to go to the Groups page listed on the sidebar.
When viewing the Your Groups tab, you can select which groups you would like to leave (or select All), then click Leave Groups.
Unsubscribe from an organization's emails
If you don't want to leave an organization, but you no longer wish to receive emails from the groups you're in, you can edit your delivery settings to only view topics on the web.