title: how to delete alarm in lightning (in js)
body: <p>I am banging my head looking at the code for ... quite some time.</p>
  
  <p>I have a lightning event, created from ics (including an alarm).
  I want to delete the alarm after something has occurred. I found calItemBase has mAlarms. But how to delete a single alarm? (there should be only one). What is the proper value of mAlarms if there is no alarm?
  What to do with mAlarmLastAck and other properties?</p>
  
  <p>My workaround is to recreate from ical without the alarm, but then the user looses categories and other things he set for the event in the UI.</p>
  
  <p>Many thanks,</p>
  
  <p>Klaus</p>