So as I undersatnd it, you've got an update notification on your samsung that you don't want to install but want the notification gone? I'd recommend installling this update and if there's something worng, they'll change it to another one. Btw, the 7.0.0 android update is now available for this model. I've got J710 and I recently switched to 7.0.0 and it's great. Yeah, there are soem things that were better in 6.0.1 but in general 7.0.0 is also good and more functional, but I'm still testing it. As for your question, if I got it right, you need to install the update if you want the notification gone. Then you should go back to the version you want with ODIN and then disable searching for updates feature. You can ask your questions on this forum
http://4pda.ru/forum/ I think they'll help you there.