From Outlook, click the File tab and select Options. A new window will appear, displaying the options menu.
From the options menu, select the Advanced tab on the left side of the page. Notice the section labeled AutoArchive. From this section, click the AutoArchive Settings button.
A window will appear showing your current AutoArchive settings. Adjust the settings however you wish--you can change how often AutoArchive is run, if expired items are to be automatically deleted, or even if you'd like to move older items to a separate folder. Once you have made sure all of your changes are correct, click OK.
To archive emails in a particular mailbox, click on the folder you wish to archive, then the Folders tab at the top of the window. From the ribbon that appears, click AutoArchive Settings.
Choose "Archive items in this folder using the default settings" or "Archive this folder using these settings". If you choose the latter, choose how often you'd like the folder cleaned out and where you'd like its contents to be moved. When you have finished, click the Apply button.