How can I cancel my expired Non-O visa extension in Thailand, and where should I go?

hey all,

I'm here on visa exempt (+extension), But have an old non-o extension (spouse of a teacher) that I did not cancel. It expired in

June.

As advised by one immigration worker, I tried to get it canceled in Chiang Mai with a letter from my spouse's work (he still works there by the way) but they did not cancel it.

a different worker asked for more details on the letter and said no need to come back, just bring it when I need an extension (a week prior I was told bring it anytime).

Now I’m in Bangkok and about to leave the country, planning to get a new non-o at the embassy back home in a few months.

I have the new detailed letter. Do you think I should go get it canceled now? If so, what should I bring and where do I go? Is it on the spot? (I don’t have much time before my flight)

Thank you so much