Remove wordpress.org from Meta widget in wordpress website

Go to folder “wp-includes/widgets/class-wp-widget-meta.php”, And comment out following section:

                        echo apply_filters(
                                'widget_meta_poweredby',
                                sprintf(
                                        '<li><a href="%1$s">%2$s</a></li>',
                                        esc_url( __( 'https://wordpress.org/' ) ),
                                        __( 'WordPress.org' )
                                ),
                                $instance
                        );

Please note that you have to do it again if you upgrade your wordpress.