If you press Winkey w combination you get a search input for Settings. Typing "notifications" I get settings to turn notifications on or off. Click there. I get a line at the bottom to enable notifications "for these apps" but there is nothing there. That may be because I have most tiles unpinned.
If you can find the tile that controls it and unpin it, that may stop the notifications just for that. I noticed when I unpinned Windows Mail I no longer got a notification for my unread mails in the Lock Screen. That may be how you turn off just one.
Either that or another poster will know the exact answer instead of guessing as I am.
I use desktop programs almost exclusively so I lack App experience.
