You can organize your references into groups. By creating a Group you are really just creating a folder where you can put all the references that you want to be collected together.
You can always delete or rename a particular group by right-clicking on it (or, use the EndNote menu option as described above).
You can organize your groups into group sets. This is a way to collect your different groups under headings of your chosing.
You can always delete or rename a particular Group Set by right clicking on it (or, use the EndNote menu option as described above).
Smart groups are built with search strategies and are dynamically updated as you add references to the library.