Well, the easiest way to do it is via a desktop client - I'd install Outlook on a box off the Unity server, connect to the Exchange server we're partnered with, log into that mailbox and move all the messages to another mailbox for review.
If you just want to toast them, you can do this fairly easily using the same mechanism or using the Message Store Manager - you didn't indicate which version of Unity you're running but I'm assuming some 4.x derivative.
You can, in fact, go through steps to just completely remove the Example administrator account from the box if you want to go that route. You need to replace references to it with a legitimate account, of course. Here's a tech tip on removing that account in a 3.x system:
http://www.cisco.com/en/US/partner/products/sw/voicesw/ps2237/products_tech_note09186a00800e25f2.shtml
the same steps work for a 4.x box as well, although it's easier to just use Global Subscriber Manager to remove it in 4.x (it launches a wizard to collect repacement references as needed).
