How to redirect user to a page after form submission

by

Please make sure these is no data output or blank spaces above wp_redirect( $final_url ); exit; otherwise this warning will always appear.

Also optionally you can use 

<?php
//Php code 
 ?>
<script type="text/javascript">
      document.location.href="http://example.com";
</script>
<?php
//php code
?>