Emma here from Shopify. Welcome to the community!
Which notifications were you wanting to turn off? Most order, shipping, and customer account notifications are sent to customers automatically, and can't be disabled, however there are a few that can be. You can see a list of which notifications can be turned off and how to do so, here.
Let us know if you have any other questions, we're always here to support you!
Emma | Shopify Social Care