title: ElasticSearch - Delete documents by specific field
body: <p>This seemingly simple task is not well-documented in the ElasticSearch documentation:</p>
  
  <p>We have an ElasticSearch instance with an index that has a field in it called <code>sourceId</code>.  What API call would I make to first, <code>GET</code> all documents with 100 in the <code>sourceId</code> field (to verify the results before deletion) and then to <code>DELETE</code> same documents?</p>