title: Mongoid Delete Document matching ID
body: <p>I'm trying to remove a duplicate document in my collection. Here's my code:</p>
  
  <pre><code>class Sites
    include Mongoid::Document
    store_in collection: "sites"
  end
  
  Sites.destroy_all(conditions: { _id: BSON::ObjectId("5685a45be4b06ab5911dcd12")})
  </code></pre>
  
  <p>Here's what is returned:</p>
  
  <pre><code>D, [2015-12-31T17:39:16.488657 #10126] DEBUG -- : MONGODB | localhost:27017 | rails.find | STARTED | {"find"=&gt;"sites", "filter"=&gt;{"conditions"=&gt;{"_id"=&gt;BSON::ObjectId('5685a45be4b06ab5911dcd12')}}}
  D, [2015-12-31T17:39:16.488946 #10126] DEBUG -- : MONGODB | localhost:27017 | rails.find | SUCCEEDED | 0.000189083s
  </code></pre>
  
  <p>But when I search the document is still there :(</p>
  
  <pre><code>{"_id"=&gt;BSON::ObjectId('5685a45be4b06ab5911dcd12'), "name"=&gt;"StackOverflow", "title"=&gt;"Stack Overflow", "type"=&gt;"Forum", "url"=&gt;"http://www.stackoverflow.com"}
  </code></pre>
  
  <p><strong>How do I permanently delete a document by reference using Mongoid?</strong></p>