title: Postgresql - update or delete a value from a nested jsonb element
body: <p>Is there a way to delete/update a nested json key object (not array)
  for example the following json:</p>
  
  <pre><code>{
    "top": {
      "nested": {
         "leaf": 1
      }
    }  
  }
  </code></pre>
  
  <p>how would I delete/update the leaf element?</p>
  
  <p>I tried </p>
  
  <p><code>SELECT jsonb '{"top": {"nested": {"leaf" : 1}}' - '{top,nested,leaf}'</code></p>
  
  <p>but no luck</p>