Upgraded to W-10; Cannot upgrade or uninstall Norton Security

I have been running Norton Security for years. I received it through my ISP, Comcast. This week, I upgraded my system to Windows 10 Pro. I received a message recommending upgrade of Norton Security. I downloaded the installer but after getting permission to run, it only goes for about 3 seconds and disappears. It leaves a Norton icon on the desktop but that doesn't appear to do anything. The upgrade reminder pops up about every 15 minutes but doesn't seem to do anything when I click on the NEXT button. Sometimes it displays a message popup that gives error code "8504, 100". Sometimes it says another installer is running.  I downloaded the uninstall tool as advised, but it says it can't find Norton Security. However, there are 3 Norton Security tasks running and there are plenty of files in C:\Program Files (x86)\Norton Security Suite\Engine64\22.5.2.15. On the other hand, there is no entry in the Programs and Features section of the Control Panel for Norton so I can't do an uninstall. It looks like I'm stuck. I can neither install nor uninstall Norton Security. It looks like I'll need to manually uninstall the files (and --shudder-- the registry entries), is that right? This has been going on for 3 days.

Can I get some assistance on this?

Thanks.