CEO's calendar is visible by all users, Windows 7 Pro, 64bit, company domain, Outlook 2010, Exchange server 2013.

Any user can add CEO's calendar to thei rown Outlook by right-clicking Shared Calendar | Add Calendar | From Address Book...

I have checked permissions under Calendar Properties and Calendar | Share... where only the default account and his Admin Asst accounts are listed.

I have checked delegation where on the Admin Asst account is listed.

I'm trying not to create a new profile...

I'm looking for other places to check to understand why any user can open up his calendar and read his appointments. As a side note, does the default account need to be set as Owner for him or can that account be removed?

Thanks