<p>Click on the group that you would like to rename, ensuring that the group is highlighted. 
Using the right mouse button, click on the highlighted group as shown
below.</p>

<img class="screenshot" src="http://www.tri-line.com/common/img/documentation/tim_professional/renaming_extension_group.png" alt="Renaming an extension group" />

<p>Select Rename using your left mouse button and overtype the existing group name
with the new name for the group.  Click away, or press Enter when you
are done editing the name.  (You can also rename a group by
highlighting it and pressing the F2 key on your keyboard).</p>