If that's what you're talking about, simply RIGHT click on the listing, choose "Delete" or "Remove from Outlook Bar". Then again, I don't use MSN so I'm not sure where you're seeing the "MSN Contacts".

Then again, do you still want the list to remain, simply not be easily visible? If that's the case, you may want to create the "Outlook Bar", but only place a few folders in that display. You can then UNCHECK the "Folder List" which can be found by clicking on "Tools", then choose "Layout".

Hope this helps.