Once you begin a print job you will notice a small printer show up on your dock. From there you can pause the printer, cancel specific jobs, etc.. Due to the speed of network and USB printing these days you are going to have to be pretty quick, since a normal document usually takes less than 30 seconds to transfer to the printer. If a document is already "in" the printer (has been transfered to the printer's internal memory), you can reset most printers by pressing cancel. Another option (in emergency situations) would be to quickly unplug the printer for at least 30 seconds (note: this may or may not work if you have a print server). Unplugging the printer is far from ideal as it may damage the printer, so try to stick to the cancel option. Hope this helps..