Norton Security Scan isn't the same as an installed antivirus. It does not integrate with your operating system and only runs when you want it to. Please read
here
So it should be safe to keep as an on-demand scanner, however you can always uninstall it if you wish.
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You didn't post the rest of the VirusTotal results that tells us what scanner found what.
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AVG will be your only running antivirus program. All those other programs are antispyware programs. Each one does something the others don't, which gives you extra layers of protection against threats. They are not heavy on system resources, either. We recommend them all. You might want to skip Spybot.