How can I revert back to a Non O visa based on marriage from a Non O retirement visa in Thailand?

First I'd wager you're not on ANY Non-O anything right now and instead if you looked at your passport you'd see your stamp says "extension of stay permitted until" and has a date

That's NOT a visa, that's an extension and you change the reason for it just like you did went you went from the original marriage extension to the retirement extension you're on now..

Keep in mind if you're still using the same immigration office where you went OFF the marriage extension and on to a retirement extension they might not let you "switch back" as most offices take a dim view of you switching reasons back and forth..

SO what you'd do is meet the requirements for the retirement extension (800K in a thai bank account in your name only for 2 months before you apply for the extension if you're using banked money method) then go to your immigration office when you have 30 days or less left on your current extension and apply for a yearly extension this time based on retirement rather than marriage.. You MIGHT need your thai wife there as they'll want to know why you're switching off the marriage extension..

Definitely go ask them months before you need to do your extension because if they say you can't do it in country, you're not gonna be able to do it and will have to exit/re-enter, then apply for the 90 day Non-O based on retirement and 2 months later apply for the new yearly extension or you'll have to exit and get a 90 day Non-O based on retirement from a nearby thai consulate..

It's all gonna come down to whether your immigration office will let you switch BACK to a visa extension you were on before you switched to the marriage extension you're on now..

Check with your office and see what they say.. People change the reason for their extensions all the time, BUT few people manage to change the reason for an extension and then change it again after a number of years 😉

I'll post the same answer here as I did on the other group you asked the question in