How can I remove image from feed?

UPDATE…

I’ll add this in the hope it might be useful for others.

Rather than trying preg replace – about which I don’t know enough – I used a function…

function remove_images( $the_excerpt_rss ) {
   $postOutput = preg_replace('/<img[^>]+./','', $the_excerpt_rss);
   return $postOutput;
}
add_filter( 'the_excerpt_rss', 'remove_images', 100 );