Click on the search button in the lower left

Type "Printer" - as you type, you'll see Printers and Scanners appear at the top of the screen

Click on Printers and Scanners 

You'll see a list of all the printers to which you are connected

(single) Click on each printer you wish to remove and choose Remove Device from the little menu (in the example below, I am removing the copier called "Arbutus 102 Copier on Eros")

Repeat as necessary until you only see the printers & copiers that you wish to keep.