พอใส่คำสั่งลบคุกกี้ก็ขึ้น Warning: Cannot modify header information - headers already sent by ทันที

<?php
session_start();
$user=$_COOKIE['user'];
$txtUsername =$_POST['txtUsername'];
//echo $txtUsername;
//$logname =$_POST['logname'];
$pw =$_POST['pw'];
$pass_md5 = md5($pw);
$name =$_POST['name'];
$email =$_POST['email'];
$address =$_POST['address'];
$sex =$_POST['sex'];
$date =$_POST['date'];
$citizen =$_POST['citizen'];
$month=$_POST['month'];
$year=$_POST['year'];
$phone =$_POST['phone'];
$occupation =$_POST['occupation'];
$status =$_POST['status'];
//echo $strUsername;
//echo $pw;
//echo $name;
//echo $email;
//echo $address;
//echo $sex;
//echo $age;
//echo $phone;
//echo $occupation;
//echo $status;
$age="$date-$month-$year";

	if(empty($txtUsername) or empty($pw) or empty($name) or empty($email) or empty($address) or empty($sex) or empty($age) or empty($phone) or empty($occupation ) or empty($status)or empty($citizen))
{echo "<script>alert('กรุณากรอกให้ครบ');window.location = 'edit_profile.php';</script>";
		exit();}
		include('function.php');
		if(!checkemail($email)){echo "<script>alert('Email ไม่ถูกต้อง');window.location = 'edit_profile.php';</script>";
		exit();}
		if(!checkID($citizen)){echo "<script>alert('Citizen ID ไม่ถูกต้อง');window.location = 'edit_profile.php';</script>";
		exit();}
		if($_SESSION['captcha']!=$_POST['capt'] || $_SESSION['captcha']=='BADCODE')
    { 
    
	echo "<script>alert('Verify code incorrect');window.location='edit_profile.php';</script>";
	exit();}


print"<div align=center><h2>submit login</h2></div><br>";
print"<div align=center>ชื่อล็อกอิน :".$txtUsername."</div><br>";
print"<div align=center>password :".$pw."</div><br>";
print"<div align=center>ชื่อ-นามสกุล :".$name."</div><br>";
print"<div align=center>e-mail :".$email."</div><br>";
print"<div align=center>ที่อยู่ :".$address."</div><br>";
print"<div align=center>เพศ :".$sex."</div><br>";
print"<div align=center>วัน/เดือน/ปีเกิด :".$age."</div><br>";
print"<div align=center>เลขบัตรประชาชน :".$citizen."</div><br>";
print"<div align=center>เบอร์โทรศัพท์ :".$phone."</div><br>";
print"<div align=center>อาชีพ :".$occupation."</div><br>";
print"<div align=center>สถานภาพ :".$status."</div><br>";
 include('config.inc.php');


$sql="update userinfo set username='$txtUsername',password='$pass_md5',name='$name',email='$email',address='$address',sex='$sex',age='$age',citizen_id='$citizen',phone='$phone',occupation='$occupation',status='$status',online='0' where username='$user'";
$result=mssql_query($sql); 

      setcookie("username", "");
      setcookie("passwd", "");

print("<div align=center><br><h3>เพิ่มข้อมูลเรียบร้อยแล้ว</h3></div><br>");
print"<div align=center><A HREF=\"index.html\">กลับไปหน้าแรก</A></div>";
  
mssql_close();
?>

</form>