Create root user in MongoDB

To create root user open the terminal then start the mongo shell

mongo

After its opened, run the following command:

use admin;
db.createUser( { 
          user: "root",
          pwd: "root",
          roles: [ "userAdminAnyDatabase",
                   "dbAdminAnyDatabase",
                   "readWriteAnyDatabase"
] } )

Change the root in user to whatever username you like and pwd to set your password.