Disable the Calendar on a User or Shared Mailbox In Exchange
This works for Office365 or an internal Exchange server to disable the calendar on a Shared Mailbox or User’s Mailbox. First, you’ll have to pull up the Exchange Management Shell. Then run the following commands:
New-OwaMailboxPolicy –Name “New Policy Name”
Creates a new mailbox policy
Set-OwaMailboxPolicy –Identity “New Policy Name” –CalendarEnabled $false
Sets the calendar for all mailboxes under the policy to be off
Set-CASMailbox –Identity “shared mailbox” –OwaMailboxPolicy “newpolicy”
Applies the policy to the mailbox in question