You can use Drush to delete all nodes of a certain type. This comes in very handy when testing migrations or imports:
drush entity:delete node --bundle=article
The response will look like this:
[success] Deleted node entity Ids: 5242, 5243, 5247, 5249, 5253, 5256, 5257, 5259, 5268, 5270, 5271, 5273, 5274, 5277, 5280, 5339, 5341, 5342, 5343, 5345, 5356, 5357, 5369, 5371, 5458, 5462, 5463, 5464, 5465, 7674, 7675, 7676, 7677, 7678, 7691, 7692, 7693, 7695, 7696, 7697, 7698, 7699, 7730, 7732, 7733, 7734, 7977, 7978, 7993, 7994, 7995, 7997, 7998, 7999, 8011, 8012, 8013, 8014, 8015, 8016, 8017, 8018, 8021, 8022, 8023