Open the print queue.
On the print job listed in the queue, right-click on it, and choose the option to purge it ("CANCEL", "purge", or "delete").
If that doesn't do it, you can stop, then start the print spooler service, and that'll probably fix it.
Let us know if just deleting it out of the queue doesn't do the job (I would restart the computer, too), and we'll direct you from there.