Block system announcements cannot be remove from home
It is possible to add more than one block of type "System Announcement" to the home page but it is not possible to remove such blocks.
Updated by Laurent Opprecht over 10 years ago
btw there is the same issue with Login.
Not sure it is actually required to make those blocks not deletable. In theory once somebody log off he will be directed to the default main page. Where a login will be present. Worse case scenario, if the login block is removed by an admin from the front page, it is still possible to log-in through the back login.