Click on your avatar where the red number is, then click Notifications and go through all of them and then click your "Back" arrow and the number will be gone. Make sure you look at all 11. Sometimes it says Show More so click that too. All gone.
Why does my profile thingy keep saying I have 11 notifications?
It's a glitch thingy. Mine only shows 3 but, before the last fix, I was showing 100 regularly.