Did you use a different Apple Account to set this up? Typically Apple requires you to cancel all subscriptions if you change country settings on your account, though AppleCare may be different (I never get it).
I am thinking you may have to have the account version that is signed into the USA. Since Apple does not provide international support you may find it very difficult to contact Apple USA about this and Apple Turkey might very well tell you that is what you need to do.
If you did create a separate account for the USA, you will have to do the canceling while signed into that account.
Remember that the people responding on the forums do not work for Apple. We are Apple products users like yourself.
Refer to this page for Apple Support features ➔ Contact - Official Apple Support
Select from the presented options until you find a solution for your issue, or see if there is a chat or phone call contact method offered lower on the page (you sometimes have to narrow down the options multiple times before this is shown). If you do not see your issue, keep experimenting with any series of selections until you reach one that offers a chat session or a telephone call and get the representative to redirect you.
This support article has various country telephone numbers for contacting Apple for support and service ➔ Contact Apple Support - Apple Support For some countries look under “Other” listing at the end of each region. Not every country has telephone support.
