Exclude post ID from WP_Query()

<?php
$query = new WP_Query( array(
    'post_type'    => 'case-study',
    'paged'        => $paged,
    'post__not_in' => array( 1, ),
) );
if ( $query->have_posts() ) {
while ( $query->have_posts() ) {
    $query->the_post();

    // do stuff

} // endwhile;
} // endif;
?>