What my AI Slop says is, "Because the statute of limitations for IRS tax audits is generally three years, fixing years 2014 through 2021 is often unnecessary unless you are contacted by the IRS."

I'm not sure I agree with @Terry53029 's AI Slop, "your client must remove the excess contribution amounts (without earnings)."  I think he has to remove the earnings also, and pay tax on them.  But then I don't know much about Roth IRA's, because they are a favorite tool of stupid people, and most of my clients are smart enough to avoid them.  Either that, or they're smart enough not to tell me if they have been getting away with funding them for years, even when not eligible. because there is no IRS enforcement to prevent it.