This is mainly a user community forum.    We could have told you how to downgrade prior to paying.  You can't downgrade yourself after paying, however.  Since nothing account-specific can be handled here, you'll need to speak by phone with TurboTax Support during business hours to see what resolution they can offer you.

Hopefully, you are in the USA.  If not, help will require a more difficult route.

Follow the steps in the FAQ below to get a call back.   There's a phone number on the page, but it may or may not be any easier.  Hours are 5AM-9PM Pacific (8AM-12 Midnight Eastern) 7 days/week.

FAQ:  What is the TurboTax phone number?

https://ttlc.intuit.com/questions/1899263