You can delete obsolete items that are Installed from DLS or modified. For whatever wisdom N3V is using, you cannot delete those long lists of obsoletes that are built-in or payware, no matter how obsolete they are. But yes, obsolete items already have a newer version in your CM, otherwise you would see something like "Newer version available". If you see that and download the newer version, then you will find the original version is now obsolete.