1. To begin, sign in to Outlook on the web (AKA Outlook Web Access or OWA).
Note: If you are already signed in to Office365, you can quickly navigate to OWA by clicking the App Launcher button in the top left corner...
Then, click the Outlook Button.
2. Next, click the Settings gear icon in the top right corner, then search for Clutter in the Settings drop-down menu, and select it.