Not quite sure about the legality of earning money as a minor, but as for being able to withdraw the money you would need a guardian since you need a couple of things(tax info, paypal/stripe, bank info, etc) which a minor might not have.
Not a lawyer, but I believe in a lot of countries, minors can’t sign contracts or trade legally without a guardian. Speak to a guardian before doing anything alone, as they know best how to do things properly without getting into legal trouble.
like what @Dark Dimension said you should ask your guardian, because I don't think just using their bank info is enough since you would also need tax info and your guardian probably needs to look into some legal precautions.
In order to sell anything on itch.io we require you to either be 18 or have an adult operating the financials of the account. This is out our terms of service that you agree when you both create an account, and when you initially set up your account for selling.
