How do I cancel my $.99/mo extra storage?

Downgrade to the free 5 GB level. See: iCloud storage upgrades and downgrades - Apple Support

I think that I set this up for my IPhone 5 or 6 but don't remember; But I still pay monthly and I have a 7 with plenty of memory. How can I find out what I am paying for each month.

How do I remove my $.99 charged? Bought a new iPhone and now I don’t need the extra space.