Below is a simple procedure for flushing a hung printing queue:
Login or switch user to root.
Issue the reject(1M) printername command to make sure no one sends any job to the printer.
Turn the power off to the printer.
If the active job appears to be causing the hang, remove it from the print queue with the cancel(1) jobnumber command and ask the owner to requeue that print job.
Shut down the print queue with the /usr/lib/lpshut command.
Remove the lock file /var/spool/lp/SCHEDLOCK and the temporary files /var/spool/lp/tmp/*/*.
Turn the printer back on.
Restart the print queue with the /usr/lib/lpsched command.