You don't HAVE to take the outside plate off the hub to remove the hub, but I find it's a LOT easier to do so, as you can't get a socket on the hub bolts with the cap in place, at least I can't, maybe with a swivel you can.
If you take the lock-out cap off, make sure you have the hub in FREE, so you don't lose the order of the parts inside.. if it all comes apart, it can be a bitch to get back together if you have never done one.