To edit a Trunk Group, use the Update trunk group: “Trunk Group Name Window”.
There are three different ways to access this window.
From the Relationships → Trunk Groups All, Disabled, or Enabled window, find the Trunk Group to be edited. Click on the Name of the Trunk Group to access the Update trunk group window.
From the Relationships → Trunk Groups All, Disabled, or Enabled window, find the Trunk Group to be edited. Find the Trunk Group to modify in the main window and move your mouse cursor to the right of the STATUS field for that Trunk Group. Left click on the three vertical dots that appear and the select Edit.
From the Relationships → Overviews → Trunk Groups window, click on the Trunk Group name in the NAME (ID) column.