image.routing.yml

image_style_delete:
  pattern: 'admin/config/media/image-styles/manage/{image_style}/delete'
  defaults:
    _entity_form: 'image_style.delete'
  requirements:
    _permission: 'administer image styles'

image_effect_delete:
  pattern: 'admin/config/media/image-styles/manage/{image_style}/effects/{image_effect}/delete'
  defaults:
    _form: '\Drupal\image\Form\ImageEffectDeleteForm'
  requirements:
    _permission: 'administer image styles'

image_style_private:
  pattern: '/system/files/styles/{image_style}/{scheme}'
  defaults:
    _controller:  '\Drupal\image\Controller\ImageStyleDownloadController::deliver'
  requirements:
    _access: 'TRUE'