What is the process for canceling a DTV visa in Thailand when switching to a Non-ED visa?

You have to apply ED plus in some embassy where you applied DTV, skip the cancelling step since you can’t cancel the DTV like as other visa. While they are checking the documents for ED plus visa, they will confirm with you if you want to void the DTV.. so they will send you voided email for the DTV ..

that doesn’t mean your DTV is canceled since, whenever you will enter Thailand, immigration officer will ask you which visa you are gonna use, so show them your voided DTV and confirm the ED plus for your entry.

The DTV visa cannot be removed in their system so far .. as my experience I always have to explain it every entry of Thailand. They said my DtV will be disappeared in their system after I’ll renew my current passport..

Why are you changing? You can go to school on any visa.

I changed from a DTV to a non-B visa.

I obtained my DTV in Hanoi, so I applied in Hanoi for the non-B visa.

In cover letter, I wrote that I wanted to cancel my DTV and change to a non-B visa.

and I submitted the DTV PDF with other documents.

I received notification of the DTV cancellation on the fifth business day, and my non-B visa was approved the following day.

In your case, I think it would be easier to apply in Hanoi for a non-ED visa.