What steps should I take after obtaining Thai citizenship while holding a work permit under my U.S. passport?

I’m seeking advice or insights from anyone who may have gone through a similar situation.

I’ve been living and working in Thailand for the past 17 years as a university instructor. I’m a U.S. citizen and have held a valid work permit and visa throughout my time here.

Recently, I officially obtained Thai citizenship through my mother, who is Thai by birth. I now have my Thai National ID card and have submitted all necessary documents to my workplace so that my employment records are now under my Thai ID instead of my U.S. passport.

Here’s where I’m unsure:

My current work permit and visa (issued under my U.S. passport) are valid until October 2025. I asked my employer what I need to do about closing or canceling them, and they told me I don’t need to do anything—that I should just let them expire since I’m now legally Thai.

That doesn’t sound quite right to me. I feel like there should be some formal process to close out the old visa and work permit under my foreign passport. I’m worried that “doing nothing” might leave a loose end or even a negative mark in the immigration system, especially if I ever need to re-enter Thailand in the future using my U.S. passport (just hypothetically).

Has anyone here been through this process or have advice on what steps I should take? Any insights would be greatly appreciated.

Thanks in advance!