KDE help: 'The screen is being locked' notification

I love the state of KDE (currently 4.9.5) on my main laptop. Mostly.

One annoying behaviour is that when I close the lid and re-open it at a later time, there is a notification waiting in the panel that says "The screen is being locked". It's about as useless as my car telling me "The doors are being locked" after I unlock it to drive back home for the day.

I looked around the settings but was unable to figure out how to stop this particular notification. Fortunately, Superuser, one of my favourite tech sites, had the answer.

As suggested by the original poster, I deviated from the instructions given by leaving the audio notification on. As it happens, I do appreciate the feedback sound verifying that the laptop is powering down for sleep.