How to hide or delete items in content area programmly

There is a requirement to show a different message depending on the day of the week in the page's header area.

For example, display "Hello Monday" on Monday, display "Hi Tuesday" on Thursday.

So I created a content area and added all messages to it and try to remove unnecessary message items in the controller.

like:

if(items[i] no need to show today){

currentPage.NotificationBlock.Items.RemoveAt(i)

}

but got error says "it's readonly property cannot remove it".

Is there some way we can do that?