What are the steps for cancelling a work permit and leaving Thailand after resigning as a teacher?

My personal experience, the admins may not like this since it's not what the law says but this what happened to me when I left and reentered the country and hadn't cancelled my WP or extension.

my NON-B extension of stay (which I've had for over 4 years, Irish passport) was due to expire on March 31st. I left the country (flight from DMK) for Indonesia on March 25th, at this stage neither my WP or extension of stay had been cancelled. On leaving the country the IO indicated that my extension of stay was expiring on March 31st and asked if I would be getting a reentry permit or not. I told the IO that I wasn't that I was finished working and he stamped me out and sent me on my way no further questions asked.

I returned to Thailand (flight to DMK from Indonesia) on April 5th. The IO officer confirmed with me that I didn't have a re-entry permit and that my NON-B was expired. I told him that was correct and that I was no longer working. He stamped me in on a 30 day wavier again no questions asked.

They prepared a letter for me that confirmed I was no longer working for them and the cancellation. They gave me this to me the day the visa was cancelled and I left within 24 hours. I understood I had to leave within 24 hours. At the border they spent about 15 mins looking at the letter and confirming it was real. Then I was stamped out and came back in 15 mins later on a visa exempt entry. Ask Mam and T. Waew what they did for me. They have done it before and know the process. Agree a cancellation date and book your bus now so you're ready to go as soon as you have the letter. I got mine around 3pm and left at 8am the next morning.

Well as it sounds nice, it all depends. Your work permit has nothing to do with your stay inside Thailand, it only allows you to work inside Thailand in combination with a Visa or an Extension of Stay based on Working. a Visa can not be cancelled, but the Extension of Stay must be cancelled. The big question now is what is inside your passport?

You must ask the HR to get the visa cancellation stamp into your passport and hand in your work permit to them ahead of time. Failing that, if they do not have your passport to get the stamp at Immigration, they can receive a letter from Immi (you must a hard copy to take with you). saying that your contract (or most likely) visa has been cancelled.

Either way, you need on of these to happen and then GO STRAIGHT to Mae Sai border - same day if possible, no delay, so book your Green Bus ticket in advance the day you know you will be going.

Hand in your passport (returned to you from HR) and all will go smoothly. The Immi officer will type into her computer the details and stamp your passport.

Proceed over into Myanmar, speak nicely and politely to the military/Immi guy, fill in visa application, hand over the money (check online how much - pay in baht for sure/ US dollars - I'm not sure) for VISA entry, then get stamp for VISA exit.

Hand back into Thailand for a visa waiver for 30 days.

It can all be done in less than one day, but you wish to stay overnight in a hotel if you can't get a Green Bus back to your destination.

Best of luck!