What is the meaning of knock off?

verb

• Get rid of (someone who may be a threat) by killing.
  • usage: "The mafia liquidated the informer"; "the double agent was neutralized"
  • synonyms: neutralize, neutralise, liquidate, waste, do in
• Cut the price of.
  • synonyms: shave
• Take by theft.
  • usage: "Someone snitched my wallet"
  • synonyms: hook, snitch, thieve, cop, glom
• Write quickly.
  • usage: "She dashed off a note to her husband saying she would not be home for supper"; "He scratched off a thank-you note to the hostess"
  • synonyms: dash off, scratch off, toss off, fling off
• Stop pursuing or acting.
  • usage: "drop a lawsuit"; "knock it off"
  • synonyms: drop