Remove custom post type slug from permalinks

remove-custom-post-type-slug-from-permalinks.php

<?php

/**
 * Remove the slug from published post permalinks. Only affect our custom post type, though.
 */

function gp_remove_cpt_slug( $post_link, $post, $leavename ) {
 
    if ( 'race' != $post->post_type || 'publish' != $post->post_status ) {
        return $post_link;
    }
 
    $post_link = str_replace( '/' . $post->post_type . '/', '/', $post_link );
 
    return $post_link;
}
add_filter( 'post_type_link', 'gp_remove_cpt_slug', 10, 3 );