Just the other day, I ran into this issue where I had a printer notification showing up in the Unity top panel of my Ubuntu 14.04 workstation. I had already got rid of any printers on my system, hence I couldn’t get rid of this notification. If I clicked on the notification it opened up the printer queue window which had an empty queue.
A search on the web led me to a couple of articles that helped me get rid of it. One of them was this answer on askubuntu.com. So here’s the 2 steps that finally got rid of it.
sudo apt-get remove indicator-printers
sudo killall unity-panel-service