cancel the three months free trial

Hi

I subscribed to the Apple music free trial and I turned off the automatic renewal. Now I want to change my store from US to KSA but apple store app asked me to cancel the music free trial before I can do that! There is no way to cancel the music free trial. I contacted apple support but they don't have any idea!

Please help me and cancel the music free trial. I don't want the music anymore. Just cancel it so I can change the store from US to KSA.