Remove classes from body_class()

gistfile1.php

<?php
/**
 * Remove classes from body_class()
 * 
 * @param  array $wp_classes
 * @return array
 */
function ja_remove_body_classes( $wp_classes ) {

    // The classes you wish to remove
    $blacklist = array( 'reply' );

    // Remove classes from array
    $wp_classes = array_diff( $wp_classes, $blacklist );

    // Return modified body class array
    return $wp_classes;

}
add_filter( 'body_class', 'ja_remove_body_classes', 10, 2 );