Sorry to hear that you are facing issues while cancelling your Adobe Stock subscription.
When you subscribe to the Adobe Stock promo offer for the first month, the first month is a free trial, Adobe doesn't charge you for the 1st month; the subscription billing actually starts from the second month.
For more information, please refer to Legal subscription terms | Adobe
I have checked your account details and noticed that your Adobe Stock subscription has been suspended due to payment issues and that is the reason you are unable to get the cancel option.
Please contact our support team Support FAQ: How can I contact Adobe for support? for further assistance.
In case you are unable to reach our support through the above-mentioned link, please see Contact Support FAQ: Unable to reach support through the "Contact US" link