Any subscription made on iOS can be managed in your iTunes account details. For more info, please see: https://support.apple.com/en-us/HT202039
I am an Adobe employee, but not a Support agent. I volunteer time here to help as I know the Lighroom iOS app well. My understanding is Adobe Support cannot issue refunds for iOS subscriptions at this time. Apple owns the transactions, and I urge you to reach out to Apple Support to inquire about a refund. Apple Support is generally great, and I hope they can help you if you explain the situation.
Please do feel free to reach out to Adobe Support directly though, to see what we can do on our side.
Using a browser that allows popups and cookies, contact adobe support by clicking here, https://helpx.adobe.com/contact.html?rghtup=autoOpen
in the chat field (lower right), type AGENT
Though Chat is usually the fastest way to get help, you can also call: https://helpx.adobe.com/contact/phone.html