To add a user, navigate to your Settings page and scroll to the Users section. Select (+) Invite User, which is located at the top-right of this section, and enter the new user's email address.

To remove a user, the admin has the ability to do so anytime from the same area. Based on the monthly Opt-in model, any user not opting in still has the ability to a read-only site from their login, including the iOS app. 

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