deleting announcements

Yes, please i second that,

Optionally it would be best to keep announcements only for a short period in WF, i.e. we also receive them in email format so we can choose to keep them or not.

Agreed. It would be great to both be able to bulk delete and have them expire as they become implemented.

Yes! I have 50 announcements right now and I have to click twice to delete each one at a time! I think this will discourage people from paying attention to notifications, if they are constantly reminded to look and it has meaningless items in there.