title: How to remove document on the basis of _id?
body: <p>I tried to delete a document using db.users.remove({_id: "4f6f244f6f35438788aa138f"})
  but this commmand doesn't delete anything.</p>
  
  <pre><code>&gt; // myobject is some document that is in our db.things collection
  &gt; db.things.remove({_id: myobject._id});
  </code></pre>
  
  <p>I am unable to figure out ' what is myobject ?' in mongodb documentation.</p>
  
  <pre><code>&gt; db.users.find()
  
  { "_id" : ObjectId("4f6cd2cb7156522f4f45b26d"), "name" : "james", "age" : 23, 
   "hobbies" : [ "cycling", "painting" ] }
  { "_id" : ObjectId("4f6cd3017156522f4f45b26e"), "name" : "john", "age" : 30 }
  { "_id" : ObjectId("4f6f244f6f35438788aa138f"), "name" : "john" }
  { "_id" : ObjectId("4f6f24556f35438788aa1390"), "name" : "john" }
  
  &gt; db.users.remove({_id: "4f6f244f6f35438788aa138f"})
  </code></pre>