To rename a group, perform the following steps:
Right-click the group that you want to rename.
Select Rename from the drop-down list to rename the group.
The group name node becomes editable.
Enter a new name for the group, and press the Enter key on your keyboard or click anywhere outside the editable field.
Alternatively:
Select the group from the left pane.
Click the Rename icon on the address book toolbar in the left pane in two-pane layout.
Select Rename from the Actions drop-down list on the address book toolbar in the left pane in three-pane layout.
The group name node becomes editable.
Enter a new name for the group, and press the Enter key on the keyboard or click anywhere outside the editable field.
The selected group is renamed.