I highly recommend you also read our terms of service, which prohibits those under 18 from selling on itch.io unless they have a legal adult managing their account. If you would like us to disable your account please say so.
Please do not start selling things without understanding the rules, it sounds like you just clicked next a bunch without reading anything during our seller onboarding.
If you are unable to get your account in good standing with our terms of service then we will be forced to close your account and refund any transactions on it, as you’ve already admitted to breaking the terms directly in this topic.