php - Issues with header while redirecting it to the current page

I have wriiten
as

            if (isset($_POST['delete'])):
 $size = count($_POST['checkbox']);

            for ($i=0; $i<=$size-1; $i++) {
 $id = $_POST['checkbox'][$i];

            $wpdb->query("DELETE FROM wp_submitted_form WHERE id =".$id);
 }

            header('Location: http://' . $_SERVER['HTTP_HOST'] .
            $_SERVER['REQUEST_URI']);
 endif;
            
?>

When
submit button is clicked it throws error message
as:

Cannot modify header information
- headers already sent by (output started at
/home/wizcorea/public_html/wp-admin/includes/template.php:1657) in
/home/wizcorea/public_html/wp-content/plugins/submitted-form/view.php on line
54

I want that page should get
refreshed after submit button is clicked

class="post-text" itemprop="text">

class="normal">Answer

Use the
rel="nofollow">ob_flush function of PHP. add this
function at the top of the
code.

ob_flush();

And
this will
work.

EDITED:

INstead
of this
code:

header('Location:
            http://' . $_SERVER['HTTP_HOST'] .
            $_SERVER['REQUEST_URI']);

Use
this code:

echo
            '';