Acrobat Reader is free.
Acrobat DC is not free. If that's what you subscribed to, you need to cancel your subscription yourself.
Be aware that if you have did subscribe to Acrobat DC and it is more than 14 days past the initial subscription date, you will be charged a cancellation fee.
If that doesn't work, you'll need to talk to customer support. This is a public forum, not Adobe support. Users, including the ACPs and MVPs, can't provide support for account, subscription, billing, download, or product activation issues. Support for those issues requires an Adobe employee.
Adobe provides support through the Chat function on the contact page or through a phone call. There is no email support.
CHAT: Click the following to contact Adobe customer support staff for help:
You must be signed in with your Adobe ID and allow cookies in your web browser for this to work. Disable any ad, pop-up, or script blockers.
This is the link to the US website. If you are not in the US, the site should redirect to the page appropriate to the region associated with your ID.
Click the chat icon at the bottom right of the page to open a chat session.
If that doesn't work, try this link, which opens a chat window directly:
PHONE: You can also search this page for a regionally appropriate phone number for customer support.