Change the location of the offline Outlook Data File (.ost) in Microsoft Outlook

Simply re-create the profile from scratch and when adding the email account for the first time, select Change Account Settings at the last step of the Wizard, and hit Next

Click More Settings

Click the Advanced Tab

Click Outlook Data File Settings

Browse to a different path for the OST file and it will prompt you to create the file there, and you’re all set!

Note: now you can clean out (maybe just move to a backup location) the old OST files at C:\Users\%username%\AppData\Local\Microsoft\Outlook