AWS Organizationsから離れる方法

I use AWS Organizations to create accounts for testing and hands-on purposes, as it eliminates the need to register payment information. However, when I needed to transfer an account built under AWS Organizations to a customer, I realized that the payment billing would still be tied to the parent account. To resolve this, I attempted to remove the account from the organization, but encountered an error message. According to AWS documentation, I need to assume a role with administrator access and then remove the member account from the organization.