Need help trying to figure out how to programmatically delete an image style in Drupal 7.
$image_style = image_style_load('IMAGE_STYLE');
image_style_delete($image_style);
See https://api.drupal.org/api/drupal/modules!image!image.module/function/image_style_delete/7
You may need to flush the image style cache before it'll let you delete it. You can do that with:
image_style_flush($image_style);
For more info, see: