To delete a group, perform the following steps:
Select the group to delete.
Click the Delete icon on the address book toolbar in the left pane in two-pane layout.
Select Delete from the Actions drop-down list on the address book toolbar in the left pane in three-pane layout.
The Delete Address Group dialog box appears requesting confirmation to delete the group.
Click Delete.
Alternatively:
Right-click the group you want to delete.
Select Delete.
The Delete Address Group window appears requesting confirmation to delete the group.
Click Delete.