1. Click the Classes tab on the left sidebar.
2. Click on the gear icon to the right of the Grade Scale drop-down menu.
3. If the grade scale is attached to a class it wont allow you to delete it. You will need to remove it from the class/classes before you can delete it.
4. Select the Grade Scale to be removed, and click the Delete button.
Note: Grade Scales that have ** can not be removed. Example **Standard