<?php
$first = 100;
$second = 200;
$third = $first + $second;
echo "Sum = ".$third;
// Destroy a variable with unset function
unset($third);
//after delete the variable call it again to test
echo "Sum = ".$third;
?>

//remove variable
unset($var1,$var2,$var3;
//remove array
unset($array['$key']);

if (($key = array_search($del_val, $messages)) !== false) { unset($messages[$key]);
}