After you create your organization, you can add people as members of the organization. You can also remove members of the organization, and reinstate former members.
You can make anyone a member of your organization using their GitHub Enterprise username or email address.
If members of your organization no longer require access to any repositories owned by the organization, you can remove them from the organization.
You can add former members to your organization, and choose whether to restore the person's former role, access permissions, forks, and settings.