mongodb add admin user

use <your database>
db.createUser({
  user: '<some username>',
  pwd: passwordPrompt(),
  roles: [{
    role: 'readWrite',
    db: '<your database>'
  }]
})

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

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