Using the Printer Software (Mac OS X) 50
Canceling printing
You can cancel a print job waiting from the computer. If the 
printing is already started, you can cancel printing by the printer.
Canceling printing by the printer
Press and hold the Pause   button for 3 seconds to reset the 
printer. 
Even when it is printing a job, the printer is reset. After resetting, 
it takes a while before the printer is in the ready state.
Note:
You cannot cancel a job waiting in the computer. To cancel a job waiting 
in the computer, see the next section “Canceling printing by the 
computer” on page 51.