You should be able to unlock these files from your end by checking the box next to the article and then clicking the "Check In" button near the top right.  This process is a safety mechanism built into the system.  When you begin editing a page, that page is marked as "Checked Out" for other users.  This prevents two people from trying to make changes to a page at the same time which would cause the first person's changes to be overwritten by the second person's changes.  When you "Close" or "Save & Close" a page, the system "Checks In" the file and releases that lock.  If the browser window is closed or the system times out before a Close or Save & Close is performed, then the file remains locked and you will need to manually "Check In" the file before it can be edited (unless you were the one editing it in the first place).