Exclude Current Post from Loop
// get the current ID:
https://developer.wordpress.org/reference/functions/get_the_id/
http://www.daretothink.co.uk/blog/exclude-current-post-from-wp-query/
<?php
$currentID = get_the_ID();
$my_query = new WP_Query( array('cat' => '1', 'showposts' => '5', 'post__not_in' => array($currentID)) );
while ( $my_query->have_posts() ) : $my_query->the_post(); ?>
<h2><a href="<?php the_permalink(); ?>"><?php the_title() ?></a></h2>
<?php the_content(); ?>
<?php endwhile; ?>