You can't, which is a good thing, because if you could, then no one else
would be able to read them!
However, this newsgroup is for questions about Access, the database product
that's part of Office Profesional. I see that you're using Outlook Express
(and that you've got a Mac): you might want to check the Mac groups to see
if someone can help you figure out how to hide the messages you've already
read.