Just ignore them. If they take legal action, do what you’re legally required to do.
You started these accounts under the company’s name. While they can request them, you have the right to refuse as long as you rename them. You cannot use a business’s name for personal accounts while using their content.
You could sell your account to them? Calculate the time you put into them and charge accordingly.
They can’t do anything, seriously. Just keep it as a personal account.