Security
Within "Client Configuration" in the Manager panel, you will find the Security option. Here you can add users, edit them, set a password, delete them, and also suspend them.
Security Screen

When Adding a user, you can assign them to a particular User Group, assigning them special roles such as Administrator, Operate-only, and View-only functions, among other pre-configurable options.
User Groups Screen

In the User Groups sub-option, you can add new specific groups and then assign users to those groups.
Groups can be Edited and/or Deleted from the main screen by clicking the three dots on a group.
Screen for Creating New User Groups

Below that is the Permissions option. Here users can assign permissions to special features.
Permissions Screen

Individual users or a user group assigned to a User Group (as seen above) can be assigned.
Individual and User Group Permission Assignment Screen

Edit a Contact Group
To Edit a contact in the address book, expand the three-dot menu that appears to the right of the contact to edit. This menu shows two options, Edit and Delete...
Users
Users belong to one or more groups which have associated permissions. This way, groups can be created that have exclusive access to certain sections and not to others...