可以使用以下SQL语句直接从数据库中删除：

delete from wp_postmeta
where meta_id in (
       select *
       from (
               select meta_id
               from wp_postmeta a
               where a.meta_key = \'blogger_blog\'
               and meta_id not in (
                       select min(meta_id)
                       from wp_postmeta b
                       where b.post_id = a.post_id
                       and b.meta_key = \'blogger_blog\'
               )
       ) as x
);

或者您可以使用php脚本来实现这一点。示例：

 <?php
define(\'WP_USE_THEMES\', false);
require(\'wp-blog-header.php\');

    define( \'WP_DEBUG_DISPLAY\', true ); 
    ini_set( \'display_errors\', true );
    $allposts = get_posts(\'numberposts=-1&post_type=post&post_status=any\');
    $keys = array(\'blogger_blog\', \'blogger_author\', \'blogger_permalink\');
    foreach ( $keys as $key ) {
        foreach( $allposts as $postinfo) {
            // Fetch array of custom field values
            $postmeta = get_post_meta($postinfo->ID, $key);

            if (!empty($postmeta) ) {
                // Delete the custom field for this post (all occurrences)
                delete_post_meta($postinfo->ID, $key);

                // Insert one and only one custom field
                update_post_meta($postinfo->ID, $key, $postmeta[0]);
            }
        }
    }
?>