You should be able to highlight multiple messages and click delete. On message list pane, if you are seeing multiple lines per message, then you are in what is called 'card view.'. Just above the message list pane, are the words 'quick filter' and an icon to the right. Click that to switch to table view and then you will see a menu bar at top of message list pane and one of the words is 'date.' CLick that to change the order of the receipt date.