@gollum,
Open the printer's print queue and stop that job. A new printer (job) icon should pop up (temporarily) in your status banner on bottom of desktop as soon as your commit the job to be printed. If this sounds foreign to you, perhaps you need someone who knows how to instruct you on basic computer use.
However the timeframe is short to stop the job, depending on how many pages you are printing. Depending on the computer's speed and the size and/or the graphical nature of your job... typically with a PC ... one page of a text job you have about 3-5 secs give or take or so to cancel the job. A photo print job, naturally, would take a bit longer to print and subsequently can be cancelled more easily (with more of a margin to stop it).