Hello JJoohhaa,
Welcome to Microsoft Community.
After I have thoroughly read everything you have posted here, I quite understand your needs at this moment.
I believe that you're older than 18, so try going directly to the Microsoft account home page:
Microsoft account | Your profile
At here, please check if you can manually change the date of birth in your account by clicking "Edit profile info":
If you still see the "Request permission" pop-up, but in fact your account does not belong to any family group, then I recommend that you contact the Family Safety Support team directly, as they have the authority to investigate your account, but we do not.
I can guide you on how to connect with them:
1.Use your private Microsoft account to access the links below:
2.Type in "Family Safety", then press Enter and click "Contact Support" at the bottom:
3.Select Microsoft 365 and office:
4.You will see contact details for Chat support and phone support, please contact them during business hours.
Best regards,
Mitchell - | Microsoft community support expert from MSFT