Remove-MailboxPermission -Identity 'CN=MyUser,CN=Users,DC=MyDomain,DC=IT' -User 'MyDomain\MyUser' -InheritanceType 'All' -AccessRights 'FullAccess'
Remove-MailboxPermission -Identity 'CN=MyUser,CN=Users,DC=MyDomain,DC=IT' -User 'MyDomain\MyUser' -InheritanceType 'All' -AccessRights 'FullAccess'