Upon deleting a message from your Outlook mailbox, these emails are automatically sent to the Trash folder, where they will remain until they are permanently deleted by the system or recovered by a user. If you would like to disable the ability to recover deleted messages, here's a quick tip on how to turn off the system feature.
From your Outlook.com home screen, click Settings > More mail settings:
Next, go to Customizing Outlook > Advanced privacy settings > Don't let me recover deleted messages:
Apply your new settings by clicking Save.