Removing from dropdown when adding a shared calendar in outlook 2011

I am trying to view colleagues shared calendars on Office 2011 and found a link for it which solved my problem, however when I add a shared folder it also adds a from field on new message sending window. This option generally messes my other co-workers as if they have the right to send an email from the list.

In Windows Outlook edition adding a shared calender does not add From filed. Is there any way to remove the from dropdown menu from New Message window on Outlook 2011?