to cut; to cut through; to sever (connections, ties); to turn off (e.g. the light); to terminate (e.g. a conversation); to hang up (the phone); to punch (a ticket)
Examples (3 in total)
携帯の電源を切って、しまいなさい。
Turn off your phone and put it away.
トムはパソコンの電源を切りました。
Tom turned off the computer.
今、あなたがパソコンの電源を切れば、地球温暖化防止に貢献できる。
If you turned off your computer right now, you would contribute to the prevention of global warming.