How to reset a string variable php code example

Example 1: php reset variable value

unset (var1, var2.... )

Example 2: php reset variable value

<?php
$xyz='w3resource.com';
echo 'Before using unset() the value of $xys is : '. $xyz.'<br>';
unset($xyz);
echo 'After using unset() the value of $xys is : '. $xyz;
?>