This is one of those annoying tasks that no one thinks about doing ahead of time, but is crucial, as you don’t want to forget and end up paying the buyer’s electricity bill for the first month. So call now to let the utility companies know that you’re moving. Ask to have all utilities taken out of your name the day of closing. Generally, you will call your city to end water, trash, and sewer service, Dominion Energy for gas service, and Rocky Mountain Power for electricity (unless you are in Provo, or Lehi--they have municipal power service). Don't forget your TV and internet provider as well. Have all of the utilities stop on the day of closing. If you have a security system, schedule it to be shut off the day before closing.
If you’re moving to a new home, transfer the utilities to your new home instead of canceling them.