do in

listen to the pronunciation of do in
İngilizce - İngilizce
To kill or end

We very nearly did in an entire keg of beer that weekend.

(Slang) kill, murder, "bump off"; swindle; cause to become extremely tired, cause exhaustion (e.g.: "That afternoon gym exercise really did me in, I slept for hours when I got home")
To do someone in means to kill them. Whoever did him in removed a man who was brave as well as ruthless. = bump off
get rid of (someone who may be a threat) by killing; "The mafia liquidated the informer"; "the double agent was neutralized"
do in