How do I remove my card or cancel my subscription?
Why can I sign up and use my card, but I literally can't find a single menu to cancel or remove my card? Why?
I think you should be able to do that from Google play, manage subscriptions. Or you can just email sololearn support and they should cancel it for you
The subscription is handled by the app store, not SoloLearn. You can cancel the subscription from the app store itself. For example, I can go to the Google Play store and see the SoloLearn pro subscription there.