Hi! For you to be added to a Microsoft family, someone with access to your email account would have needed to accept the family invitation. You cannot be added to a family without that step. If you are a minor, you should check with your parents about this, since support is not able to remove you from the Microsoft family.
If the account is an adult account, then you should be able to remove yourself from the family. Being added as a family member does not change the age setting of the account.