You’re going to need to be a little more specific, though: SmartThings has several different kinds of notifications, managed in different ways.
If these are notifications from the built in security feature, SmartThings Home Monutor (STHM), then here’s the FAQ for that (the topic title is a clickable link.)
If it’s some other kind of notification, it would be done a different way, if it’s possible. Can you post a screenshot of a notification?
Also, the Arlo integration was updated a few months ago, so posts in the forum that are older than December 2020 may no longer apply. please see the following thread where you will find people currently using Arlo with SmartThings.