Hi inajam,
Norton Antivirus is a component of Norton 360. Norton will not allow you to install two versions of the same Norton product. If you want to keep Norton 360, uninstall the Norton AV and reinstall N360. You can get a product refund if you qualify, here:
https://support.norton.com/sp/en/us/home/current/solutions/kb20100512172507EN_EndUserProfile_en_us