How can I remove nodes? How can I remove nodes using Drupal Console?
Drupal Console is for creating boilerplate code (also known as scaffolding) rather than for general administration and day-to-day work.  You can see an overview of the features of Drupal Console: 

How does Drupal Console help?

To delete a node you would be advised to use drush which is a general purpose DRUpal SHell. Drush doesn't have a command to do this out of the box but there are a number of different approaches outlined in this post,
Can I delete nodes of a given content type with Drush?