KB10392143
Open Outlook and click on Tools Options
Now click on the Other tab and click the AutoArchive button.
This opens up a whole menu of options and settings to pick from:
you can choose how often AutoArchive runs in X days. Also confirm how old the archived emails should be under During AutoArchive
Once its all configured Make sure to click the Apply these settings to all folders now button
Once you are done go to File then Archive
Click the Mailbox and then Ok
after you hit Ok the above window will go away
Look down into the bottom corner of Outlook and you will see this Archiving animation
Once the Archiving animation disappears you are done