How do I stop this purchased app it s been taking 9.99 from account every month and I need ito put a stop to it please

My son was using my phone and accidentally purchased the weather app and I did not know till I checked my apple account to see why they been taking out 9.99 for 5 months that equals to $50 could you please refund my purchases and delete the weather app because I don’t use it at all thank you very much.