how do I cancel my sky sports tv subscription?

I have paid an in-app purchase of £4.99 with SKY Sports TV and it says it is in use until August 10th. I clicked a 1-month subscription and I need to check if that is just one month of if it's rolling? I can't see a way of cancelling it. Does anyone know if it is necessary to cancel and if so please how do I do it?? It takes me to iTunes and there is no cancellation there either?

Thank you

Lorri 🙂