The Norton Removal Tool will scour your PC for remnants of any Norton security tool (all the old Norton 2003 and later products), removing any associated files, folders and Registry keys.
The application's uninstall program really should handle this, of course, but security tools are notorious for worming their way deep into your PC, and getting rid of them is rarely straightforward. But if you don't, then you may have problems elsewhere: some security suites won't install if they detect the remains of a competing package, for example.
Before you use the Removal Tool, though, take a moment to think. Do you really want to wipe everything? You'll lose all your program settings, quarantined files and other associated data. Your product key will be deleted, too - if you ever plan to reinstall your Norton package, and you don't have a record of the key to hand, then you must make a note of it now.
With that done, all you have to do is download the Removal Tool, run it, follow the instructions and wait. Perhaps for a while, as the program can take 5 to 10 minutes to do its work, but be patient and before long your system will become a Norton-free zone.
Norton Removal Tool will now remove all Norton products, including the 2017/8 range.