I don't think you can cancel it, perhaps at the consulate that issued it it may be possible. They could reject your DTV application or perhaps more likely sit on it until the tourist visa expires but that's a long time to sit in jakarta
what checking in part? There is no checking in part. You automatically become a Thai tax resident if you spend 180 days or more inside Thailand in a calendar year. If you don't spend 180 days or more in a calendar year then you are not a Thai tax resident that year.
I clearly understood the question but the reality is without knowing which country he is from and looking at the tax rules for that country its impossible to be specific
Stop fishing and just go with your actual situation then you won't have a problem. If you can't show earnings you can't use workation. If you use soft power you still can be asked for evidence as to how you will support yourself. Bottom line is no matter what you do you are likely going to have to show income. They want 3 months of statements but only the final month needs 500k