VK360@VK360:~$ mongoimport --db cstore --collection stores --drop --file /home/kuliza360/Desktop/Office/Cstoredemo/my_data.json
2018-04-04T10:37:41.545+0530    connected to: localhost
2018-04-04T10:37:41.545+0530    dropping: cstore.stores
2018-04-04T10:37:41.545+0530    Failed: not authorized on cstore to execute command { drop: "stores" }
2018-04-04T10:37:41.545+0530    imported 0 documents

use admin
db.createUser(
  {
    user: "admin",
    pwd: "password",
    roles: [ { role: "root", db: "admin" } ]
  }
);
exit;

2018-04-04T10:33:58.124+0530 E QUERY    [thread1] Error: couldn't add user: not authorized on admin to execute command { createUser: "admin", pwd: "xxx", roles: [ { role: "root", db: "admin" } ], digestPassword: false, writeConcern: { w: "majority", wtimeout: 60000.0 } } :
_getErrorWithCode@src/mongo/shell/utils.js:25:13
DB.prototype.createUser@src/mongo/shell/db.js:1267:15
@(shell):1:1