title: Apollo cache modify doesn't delete the cached item field when DELETE sentinel object is returned
body: <p>I'm trying to delete a field in the cached item by using the <strong>cache.modify</strong> method like it's described in the <a href="https://www.apollographql.com/docs/react/caching/cache-interaction#example-deleting-a-field-from-a-cached-object" rel="nofollow noreferrer">official documentation</a>. <br>Based on the API docs I should return the
  <a href="https://www.apollographql.com/docs/react/api/cache/InMemoryCache/#delete" rel="nofollow noreferrer">DELETE sentinel object</a> from the <code>resolver</code> function that reflects the type field I want to delete.</p>
  <p>I'm doing it but the required field still exists in the cached item after the execution. <br> How it's possible? Have I just missed something?</p>
  <p>Here is the code example:</p>
  <p>I have this item in the cache</p>
  <pre><code>{
    __typename:&quot;Module&quot;
    id:&quot;l_14&quot;
    length:223
    title: &quot;Chris Hadfield&quot;
  }
  </code></pre>
  <p>and I want to delete the <code>title</code> field so I tried to use the <code>cache.modify</code> as described in the docs. Here is how it looks:</p>
  <pre><code>  client.cache.modify({
      id: 'Module:l_14',
      fields: {
        title(data, { DELETE }) {
          return DELETE;
        },
      },
    });
  </code></pre>
  <p>But after the execution, the appropriate Module item in the cache didn't change. The <code>title</code> field hadn't been deleted. It looks exactly like it was before the execution:</p>
  <pre><code>{
    __typename:&quot;Module&quot;
    id:&quot;l_14&quot;
    length:223
    title: &quot;Chris Hadfield&quot;
  }
  </code></pre>
  <p>So why the <code>title</code> field hadn't been deleted even when I replicated all the steps from the documentation example? <br><br>
  P.S. I'm not sure if it's relevant, probably not, but just in case: this Item doesn't have a direct mutation etc. in the BE schema. It's just a nested object of the parent one. The schema looks like this:</p>
  <pre><code>  type Track {
      id: ID!
      title: String!
      author: Author!
      thumbnail: String
      length: Int
      modulesCount: Int
      description: String
      numberOfViews: Int
      modules: [Module!]!
    }
  
    type Module {
      id: ID!
      title: String!
      length: Int  
     }
  
  </code></pre>
  <p>Thanks for any help!</p>