For some reason it seems an online directory (form of an address book) has been setup. You could try this.
- On the
Tools menu, click
E-mail Accounts.
- Under Directory, select
View or change existing directories or address books, and then click
Next.
- Click the address book you want to delete. (Should be labled as
Lightweight Directory Access Protocol [LDAP] account).
- Click
Remove.
It's just like removing an e-mail address really. Hope it works!
/ 
