knock off

get rid of (someone who may be a threat) by killing

• “The mafia liquidated the informer”
• “the double agent was neutralized”

cut the price of

take by theft

• “Someone snitched my wallet!”

write quickly

• “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”

stop pursuing or acting

• “drop a lawsuit”
• “knock it off!”