Pull an element in sub of sub-array in MongoDB?

To pull an element, use $pull along with $(positional) operator. Let us create a collection with documents −

> db.demo679.insertOne(
...    {
...       id:1,
...       "details": [
...          {
...             CountryName:"US",
...             "information": [
...
...                { "Name": "Chris", "FirstName": "Name=Chris" },
...
...                {"Name": "Bob", "FirstName": "Name=Bob" }
...             ]
...          },
...          {
...             CountryName:"UK",
...             "information": [
...
...                { "Name": "Robert", "FirstName": "Name=Robert" },
...
...                {"Name": "Sam", "FirstName": "Name=Sam" }
...             ]
...          }
...       ]
...    }
... );
{
   "acknowledged" : true,
   "insertedId" : ObjectId("5ea442cf04263e90dac943fd")
}

Display all documents from a collection with the help of find() method −

> db.demo679.find();

This will produce the following output −

{ "_id" : ObjectId("5ea442cf04263e90dac943fd"), "id" : 1, "details" : [
   { "CountryName" : "US", "information" :  [
      { "Name" : "Chris", "FirstName" : "Name=Chris" },
      { "Name" : "Bob", "FirstName" : "Name=Bob" }
   ] },
   { "CountryName" : "UK", "information" : [
      { "Name" : "Robert", "FirstName" : "Name=Robert" },
      { "Name" : "Sam", "FirstName" : "Name=Sam" }
   ] } 
] }

Following is the query to pull an element in sub of sub-array in MongoDB −

> db.demo679.update(
...    { "details.CountryName":"US" },
...    { $pull: { 'details.$.information': { "Name" : "Bob", "FirstName" : "Name=Bob" } } }
... );
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

Display all documents from a collection with the help of find() method −

> db.demo679.find().pretty();

This will produce the following output −

{
   "_id" : ObjectId("5ea442cf04263e90dac943fd"),
   "id" : 1,
   "details" : [
      {
         "CountryName" : "US",
         "information" : [
            {
               "Name" : "Chris",
               "FirstName" : "Name=Chris"
            }
         ]
      },
      {
         "CountryName" : "UK",
         "information" : [
            {
               "Name" : "Robert",
               "FirstName" : "Name=Robert"
            },
            {
               "Name" : "Sam",
               "FirstName" : "Name=Sam"
            }
         ]
      }
   ]
}