title: Delete a child record from a specific parent record
body: <p>I am pretty new to mongodb.  I have 3 levels of documents. </p>
  
  <p>Parent > Child > Child, all having _id field.</p>
  
  <pre><code>{
      "_id" : "n2qw5sojs4bajrj",
      "Title" : "Mr",
      "Instance" : "HQ",
      "FirstName" : "ppp",
      "LastName" : "uuuu",
      "Position" : "BF",
      "EmailAddress" : "xxx@ppp.com",
      "Requests" : [ 
          {
              "_id" : "121",
              "Date" : "12/02/2018",
              "Status" : "New",
              "ApprovedBy" : {
                  "_id" : "sdfsdf",
                  "Name" : "MAN"
              },
              "PPE" : [ 
                  {
                      "_id" : "121",
                      "Code" : "PPE",
                      "Status" : "New",
                      "Title" : "Trousers",
                      "Type" : "STD",
                      "Size" : "10111116",
                      "Qty" : 1,
                      "LostDamage" : {
                          "Reason" : "asdaD",
                          "Location" : "Station",
                          "Damage" : "Damged"
                      }
                  }, 
                  {
                      "_id" : "122",
                      "Code" : "PPEOPP",
                      "Status" : "New",
                      "Title" : "TrousASDASDASDers",
                      "Type" : "STD",
                      "Size" : "10111116",
                      "Qty" : 1,
                      "LostDamage" : {
                          "Reason" : "asdaD",
                          "Location" : "Station",
                          "Damage" : "Damged"
                      }
                  }
              ]
          }
      ]
  }
  </code></pre>
  
  <p>I would like find out how to delete the last PPE Element (Parent > Request > PPE) by the _id column.</p>
  
  <p>So I would to delete the following child:</p>
  
  <pre><code>{
                          "_id" : "121",
                          "Code" : "PPE",
                          "Status" : "New",
                          "Title" : "Trousers",
                          "Type" : "STD",
                          "Size" : "10111116",
                          "Qty" : 1,
                          "LostDamage" : {
                              "Reason" : "asdaD",
                              "Location" : "Station",
                              "Damage" : "Damged"
                          }
                      }
  </code></pre>
  
  <p>Any tips / help would be great.</p>
  
  <p>Thanks
  Paul</p>