How to automatically clear Outlook OWA trash folder when signing out?

Step 1: Sign into https://portal.office.com/

Step 2: Navigate to Outlook web app or access https://outlook.office365.com/

Step 3: Click on the settings gear icon on the top-right corener of the page and select View all Outlook settings.

Step 4: Switch to message handling tab and check the Empty my deleted items folder checkbox.