Years ago before I invested in a smartphone and still had the flip kind, Facebook and Twitter came along opening new lines of communication online. When they first started (Twitter especially), smartphones were for the rich or uber-geeks, so FB and Twitter created notifications via email and text message to keep you in the loop when you were away from the computer.
I managed several pages on FB and accounts on Twitter, so I created both email and text notifications. Now that I and practically everyone in the world have smartphones we have apps for both products which provide their own notifications.
Because I never went to their web sites anymore, I neglected to disable the email and text notifications and the result was notification overload. I ignored it for several years, but decided to finally get rid of the duplicate notices. It is pretty simple, but you have to go to the web sites to disable them.
I hope you find this article useful,