Need to uninstall Symantec Endpoint Protection

I have an iMac running 64-bit Windows 8 Pro through Parallels Desktop 8. I tried to install a Windows 7/Vista/XP version of Symantec Endpoint Protection (64-bit client), but found out that it wouldn't install because it doesn't work under Windows 8 (so much for backward compatibility). So I gave up and purchased/downloaded Norton Internet Security, but it won't install until I uninstall SEP.  I've tried uninstalling SEP through the Control Panel numerous times, restarting the computer as well.  SEP is still there and NIS still won't install. Chatting with "Nathan" didn't help as the Norton Removal Tool told me I had to uninstall "Symantec Antivirus 9 or later". Trouble is SEP is the only Symantec/Norton product listed as being installed, which as I mentioned earlier, refuses to uninstall. I sure hope someone can tell me how to get out of this mess.