"$GLOBALS - Contains a reference to every variable which is currently available within the global scope of the script. The keys of this array are the names of the global variables." (c) http://www.php.net/manual/en/language.variables.predefined.php

With unset($GLOBALS['varname']); you unset the reference, not the variable itself, which is equal to:
<?php
$var = "string";
$ref =& $var;
unset($ref); //unset the reference
var_dump($var); //but the $var is still here
?>

You are wrong. unset($GLOBALS["variable"]) is the recommended way to remove global variables from within a function, it does NOT remove local references. To prove my point, the PHP manual states this here:

http://www.php.net/distributions/manual/php_manual_en.html.gz#function.unset

If you would like to unset() a global variable inside of a function, you can use the $GLOBALS array to do so: 

<?php
function foo() 
{
    unset($GLOBALS['bar']);
}

$bar = "something";
foo();
?>
 
_______________________________________

So that is exactly what I was doing, but I was trying to unset a 2 dimensional array rather than a simple variable, and it does not work like it should.

The PHP manual also states:

Handling of global variables
While handling of global variables had the focus on to be easy in PHP 3 and early versions of PHP 4, the focus has changed to be more secure. While in PHP 3 the following example worked fine, in PHP 4 it has to be unset(unset($GLOBALS["id"]));. This is only one issue of global variable handling. You should always have used $GLOBALS, with newer versions of PHP 4 you are forced to do so in most cases. Read more on this subject in the global references section.