if you are absolutely certain that you have no other plugin or code that relies on the wppizza javascript to be loaded on the page you can do this

function wpdocs_dequeue_script() {
wp_dequeue_script('wppizza');
wp_dequeue_script('wppizza-validate');
}
add_action( 'wp_print_scripts', 'wpdocs_dequeue_script', 100 );