您可以尝试通过customize_controls_print_footer_scripts 挂钩：

/**
 * Change the url of the Close link in the /wp-admin/customize.php page
 * See http://wordpress.stackexchange.com/q/116257
 */
function change_close_url_wpse_116257() {
    $url = get_admin_url(); // Edit this to your needs
    printf( "<script>
                jQuery(document).ready( function(){ 
                    jQuery(\'#customize-header-actions a.back.button\').attr(\'href\', \'%s\'); 
                });
            </script>"
            , esc_js( $url ) );     
}
add_action( \'customize_controls_print_footer_scripts\', \'change_close_url_wpse_116257\' );