When a Client has completed all work for the foreseeable future, it can be a good option to close that Client out. Doing this changes the text and icon for the Client in the hierarchy to light gray, and prevents any further automated communications to send out for the Client and all entities beneath it.
To close a Client out, click the toggle on the Client's home tab labeled "Client Status" from "Open" to "Closed".
Note: Archiving a closed Client using the button on the bottom right of the home tab will automatically hide them from your hierarchy view. All Contracts, Projects, and Subprojects must also be closed out and all Projects and Subprojects must be archived in order to do this.