Validation

You can de-enqueue the validation script. There is a fall back validation that just check for name and email.

function esu_dequeue_script() {
   wp_dequeue_script( 'esu_js_url' );
}
add_action( 'wp_print_scripts', 'esu_dequeue_script', 100 );

This could go into your themes functions.php file or you could create a small plugin to house this action.

Cheers !