I'm not 100% sure about this but I believe you could suspend the accounts and then start 4 new ones with the intention of cancelling them once you have your new teams. Obviously, don't suspend the account that will do the boosting if that is your plan.

Edit: Nevermind.

http://us.blizzard.com/support/artic...ategoryId=2317

"At this time we do not offer the ability to pause or suspend access to an account. Once your billing cycle begins using the payment method you have chosen it can not be reversed or refunded. You will still be able to access the account and characters for the duration of your pre-paid time.

If you need to take a break from World of Warcraft and are using a credit card for payment you can temporarily cancel your subscription so that you will not be billed further. This can be accomplished through your Account Management page."