title: sidekiq to cancel list to scheduled jobs
body: <p>I have several scheduled jobs running like this:</p>
  
  <pre><code>MyWorker.perform_at(3.hours.from_now, 'mike', 1)
  </code></pre>
  
  <p>I am wondering, if later, say an hour later, I feel like I want to cancel this job, how would I go about doing that?</p>