That's pretty useful qwerty12. I had a huge number of events, many of which used the same cookie. I tried this command to clear them out gracefully:

sed -ne 's/[^>]*cookie[^>]*>\([[:digit:]]*\)<.*/\1/pg' \
/var/lib/alarmd/alarm_queue.xml | sort | uniq | \
while read i; do alarmtool -r $i; done

But the /var/lib/alarmd/alarm_queue.xml file was not empty. Clearly alarmtool has issues.