Turn off all notifications. Slowly turn back on the ones you miss. After a few weeks you’ll only get those from the people you most love and the (few!) services you regularly need. New information can no longer be “pushed” to you; you decide when to pull it.
You will be much slower to respond to everything else. At times this will frustrate those used to the status quo of entering each other’s consciousness at-will by simple finger-tapping. But you have the right not to be pushed.