That’s also why I have mentioned in other posts why are people so eager to get a Thai TIN it nearly doesn’t make sense to get one, even if you do become a tax resident or not the ch aces of actually being liable for any tax in Thailand on a DTV is next to 0
You need to contact the embassy who issued your DTV , send a copy of your passport bio page. Latest entry and exit stamp ( try to go through a manual lane to get a stamp so you can prove you are not in Thailand )Visa and explain why you are canceling it ( perhaps a letter from your perspective employer) it took me about 10 days to have it “voided”