iCloud won't let me delete the backup from my old iPhone

I just upgraded from my old iphone 4S to a new iphone 5S. I used the backup from my old phone to setup the new phone. Now I would like to turn iCloud backup on for the new phone but I can't b/c I don't have enough storage available in iCloud. So I go iCloud to manage the storage and the backup from my old phone is sitting there (I've wiped that phone already and turned it off). I selected that backup and choose delete, but I get an error message that I can't delete it b/c it is still in use. What? How do I convince iCloud that it is no longer in use? I rebooted the new phone and my laptop and tried this all again. I also made a backup on my laptop of the new phone. That also didn't help. So, in summary, old phone is dead but icloud won't let me delete the backup for it.