Sorry to hear that you are facing issues while cancelling your Adobe Stock subscription.
I have checked your account details and noticed that you have signed up Adobe Stock-750 images per month plan on 17 Jul 2018.
If you wish to cancel your Adobe Stock subscription, please refer to the help document Cancel your Adobe Stock membership to understand the workflow of the cancellation.
You may also contact our support team Support FAQ: How can I contact Adobe for support? for the cancellation requests.
In case you are unable to reach our support team through the above-mentioned link, please see Contact Support FAQ: Unable to reach support through the "Contact US" link
If you still face any trouble, feel free to update this thread.