I want to stop any charge for I tunes.

Here is simple steps to stop it:

1. Open Settings, >> iTunes & App Store.
2. Apple ID at the top >> Tap View Apple ID and sign in if prompted.
3. Tap Subscriptions >> Find and tap the subscription you would like to cancel.
4. Choose Cancel Subscription

Second: How to use it free:

• Open iTunes >> iTunes Store item on the left-hand sidebar.
• iTunes Store homepage >> Quick Links heading on the right side.
• Underneath that heading will be a Free On iTunes link

I hope it will be helpful for you.