Trial ends after the first month. You get charged the second month, but still can cancel during the first 14 days into the paid subscription, and you will be refunded. Thereafter, you have a one-year subscription of Adobe stock, that you can cancel anytime by paying half of the remaining due. This is clearly all noted in the one page (on my computer screen) terms and conditions. You did agree to those terms.
Now, if you really don't use the service, you may try contacting Adobe customer care and negotiate your way out of this contract at the least cost for you. Good luck.
Adobe customer care can be contacted by beginning a secure chat session at https://helpx.adobe.com/contact.html?rghtup=autoOpen. Pop-up blockers need to be disabled! If the chat window fails to open, or is non-responsive, use a different device to start the interaction.
Support phone numbers may be found here: https://helpx.adobe.com/contact/phone.html. Please note that phone charges may apply.
(see also here: https://community.adobe.com/t5/creative-cloud-services/how-to-contact-adobe-support/td-p/11875703 or here
https://community.adobe.com/t5/account-payment-plan/how-to-contact-adobe-support/td-p/11843852)