Removing pst files from an Outlook profile outside of Outlook client

1. Search for Control Panel and open it
   
2. Change the View By field to Large Icons
   
3. Select Mail applet
   
4. Select Email Accounts
   
   
5. Select Data Files tab
   NOTE: The next step will not delete these files from the storage location, but will remove the association with Outlook to allow it to start.
6. Select listed file containing \\?\UNC at the start of the Location path
7. Click Remove
8. Repeat Steps 6 - 7 for remaining Locations starting with \\?\UNC
9. Click Close on all open windows
   
10. Open Outlook as normal

For step by step instruction (including screen shots) on how to open a specific PST file see the opening a PST file page.