Amazon — want to cancel a magazine subscription

Address:

34974

I have tried to cancel a magazine subscription and haven't been successful. I do not want it anymore. There is a $4.34 amount charged on my credit card every month. This is an outrageous amount for a magazine. Please tell me how to do it.
Thank you.

I don't know what this number is:
15wvfn0k9ah

I hope you can tell me how to cancel my subscription as soon as possible.