Well you can't.
So stop moaning and just accept that drugs are another facet of society now.
Booze is a drug too. A very deadly one. And it's legal.
Killing/arresting a few thousand dealers on the streets of Thailand isn't going to even put a dent in the transborder drugs trade. It will still continue unabated so what is the point in having another deadly war on drugs, where innocent civilians could potentially get caught up in the crossfire?
Supply & demand trumps all!