One of the frustrating things with Mac OS is that you cannot uninstall an application completely in the sense that there will always be remnants of files scattered all around your system and unless the application comes with an uninstall application, you will have to painstakingly remove files manually by yourself for who knows how many there are.
This was the case when I tried to uninstall Norton Antivirus for Mac OS. I just wanted to see how the app works. When I found out it was useless since it never ran, I uninstalled it right away. I always use Amnesia to remove applications and all its related files but after I rebooted my laptop, it ran a Norton QuickMenu application. There I suspected that there were still remnants of it scattered around.
I searched and searched and finally, I was lucky enough to come across this page on how to uninstall Norton Antivirus for Mac OS completely. Go to this link and follow the instructions. Do not be surprised at the number of instructions that you need to do. The step by step details are very short instructions on what you need to do in your system running Mac OS.