釜底抽薪
Take away fuel, take away flame(fire) .

eg：Mark changed his subject to calm the angry crowd, to take away fuel is to take away flame.

中英俚语俗语来源：魏收·为侯景叛移梁朝文：“抽薪止沸，剪草除根。”

反义词：火上浇油 Pour oil on the flame.