Q: how do i cancel my current icloud email address and create a new one?

To create a new iCloud email address you would have to create a new iCloud account.  However, you can create up to three email alias addresses which can be used just like your main iCloud email address, and will receive email in your current inbox.  This explains how to create and alias address: http://support.apple.com/kb/PH2622.

Be aware that once you create an alias address it cannot later be used to create a new iCloud account, nor can it be moved to another account.  You also can't reactivate it if you ever delete it.