This is what used to be called Yahoo Mail Plus and various other things over the years. You can cancel it, but not through Answers. You have to do it in another part of Yahoo.
Sounds like you signed up for the Yahoo Mail pro which eliminates ads and gives you some extra services.
Contact your Financial Institution (Card issuer) and Dispute the Charge.
You will then have a few weeks to PROVE you did not authorize the debt.
We have no idea. You must have authorized it.
Cancel your Yahoo Mail Pro subscription From the Yahoo Mail app
Tap the Menu icon Image of the Sidebar menu icon..
Tap Manage subscription.
Tap Cancel subscription.
Follow the onscreen prompts to finish canceling the service.
You obviously signed up for it though
Who are you talking to? We are not Yahoo customer service.