Hey @lrose07! Welcome to the Spotify Community. ^^
Subscriptions to Spotify premium through iTunes are more expensive than suscribe in Spotify.com.
Because Apple get 30% from every transaction.
To change your subscription from itunes to the 9.99 subscription, you will need to cancel your itunes subscription. You can do this by following the steps here. Then you have to resubscribe by going to the upgrade page.