"This group of folders is associated with an e-mail account. To remove the account, click the File Tab, and on the Info tab, click Account Settings. Select the e-mail account, and then click Remove."
However Outlooks suggestion dosn't work either, cause the mailbox is not visible under the E-mail accounts.
Well, I've seen this "error" several times, Googeling it has provided me with a lot of different answers. Everything from recreating the Outlook profile to editing the registry.
Recreating the profile solves the problem until your mailbox is fully synced with the Exchange server again.
Editing the registry (HKCU\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles\Default) will cause your Outlook to hang when it starts, because you actually create a mismatch between your Outlook and the Excahange server. BTW: The Exchange server wins..
Here is the PERMANENT fix for all of you that just can't get theese mailboxes out of Outlook:
Ask your system administrator to remove your name from the "Full access" permissions of the mailbox in question.
If YOU are the administrator:
1 - Open EMC (Exchange Management Console)
2 - Expand your server - Recipient Configuration - Mailbox
3 - Find the Mailbox in question - Click it
4 - Click "Manage Full Access Permission..."
5 - Mark the user in question, click on the red X
6 - Click Manage
Ask the user to close his/hers Outlook, wait 10-15 sec (Outlook "hangs" a little on exit) and reopen Outlook. The Mailbox will now disappear after Outlook finishes the sync with the exchange server.