Get your taxes done using TurboTax

I accidentally filed non filers thinking it was for the stimulus check. I have been getting mixed information as to how to fix this problem. Do I mail In my taxes and add a cover letter to it explaining error or do I amend my taxes. But how do you amend something that was rejected, therefore not field. The only one filed is the nonfilers one that I did in error but how do you amend that one? Need help