Magento 2 Remove SampleData failed

I have installed Magento 2.2.4 with sample data. Now I need to remove all sample data, and I found a solution from Magento DevDoc

I used command as suggested,

php bin/magento sampledata:remove 

But I got this error as following,

Loading composer repositories with package information

Removal failed, reverting ./composer.json to its original content.


  [ComposerDownloaderTransportException]                                   
  The 'https://repo.magento.com/packages.json' URL required authentication.  
  You must be using the interactive console to authenticate 

What did I miss?