Are you talking about tiles? Just right-click them -> Unpin, Uninstall or Resize. You can right-click a bunch of them and unpin all of them at once. You can set up the mail accounts including Gmail in Settings (swing mouse around lower right corner), or just pin the Gmail website to Start (right-click -> pin in "new" IE, or "gear button" -> Pin to Start in desktop IE).
For the most part, if there's something you can't find it's probably either in the right-click commands or in the Charms (search/share/devices/settings). Once you get comfortable with those two things you're pretty set.
But hey, if Classic Shell (or Win7) works better for you, great.