You can add, remove and update user rights by clicking "User management" in the top bar of the giosg console.Choose "Users" and you can see a list of all users.
Click "+New user" to create a new user, and fill in the email address of the user. This sends a registration link to that email. The link is valid for 48h.
You can define the user rights for each user and edit their information by opening the information of that user. You can also delete users here, and set them offline in the chat if needed.