<form method=post action=del.php>
<input type=hidden name=myvalue value=X>
<input type=submit name=submit value=YES>
<input type=submit name=submit value=NO>
</form>
if(isset($_POST['submit'])=="YES"){
$query=mysql_query("delete from mytable where field='$myvalue';");
}else if(isset($_POST['submit'])=="NO"){
print 'حذف نمی کنیم.';
}
<?php $myvalue ?>