To begin deleting a class or group within LivingTree first select the class you would like to delete on the left hand side bar. You will find the class under the 'Groups' section.
Next select "My Network" from the top navigation bar.
From the Class's network page select the pencil Icon located in the top right hand corner.
This will then give you the edit screen for the class where you will get the option to delete this class and/or group.