Reply To: Caption for post thumbnails

[Tom]

Looks like you’re using the blog add-on, which requires a slightly different function to remove the initial one:

add_action('after_setup_theme','generate_remove_blog_post_image');
function generate_remove_blog_post_image()
{
      remove_action( 'generate_after_entry_header', 'generate_blog_post_image' );
}

Hopefully that does it for you 🙂