It would have been a big deal at the time and you'd have meet in person with a CAA, taken foreign passport and identifying documentation. CAA's have immense responsibility under IRS rules and consequently are advanced practitioners with a great deal of expertise.
I did all of this for my spouse and it really was an in-depth investigation, thorough and professional. (CAA had about 30 years in the profession)
Once you revoke the election there is no going back - EVER.... So be sure it's what you want. I have a feeling, although i'm sure those in the know will jump in... You can't elect for the previous year, (2021) and only the current year. Reason - if your wife had a substantial income, won the lottery etc, she can't then 'come out' of the U.S. tax system and not pay up on that income.
You need to write a formal letter, thay you both sign to revoke, so a mail in tax return/letter