Hello, Jessica Buenrostro
Welcome to the Microsoft community.
Thank you for your feedback. I understand that you are experiencing issues with the administrator name. You can try the following:
Log in to your account (needs to be an administrator account), search for Control Panel in the search bar, click on User Accounts, click on Remove user accounts, click on your son's account, there is an option on there to delete the account and change the username.
Please let me know if my understanding is wrong.
I look forward to your feedback.
Best Regards,
Aaron| Microsoft Community Support Specialist