<?php
$files = array(array(
	"REDUNDANT" => "Yes",
	"FILE_NAME" => "book (2).pdf"),array(
	"REDUNDANT" => "No",
	"FILE_NAME" => "51894a (2).pdf"));

echo "Before Update loop\n-------------------------------\n";
echo "<pre>";
print_r($files);
foreach($files as $key => $file){
   if($file['REDUNDANT'] == "Yes"){
       unset($files[$key]);
   }
}
$files = array_values($files);
echo "After Update loop\n----------------------------\n";
echo "<pre>";
print_r($files);

Before Update loop
-------------------------------
<pre>Array
(
    [0] => Array
        (
            [REDUNDANT] => Yes
            [FILE_NAME] => book (2).pdf
        )

    [1] => Array
        (
            [REDUNDANT] => No
            [FILE_NAME] => 51894a (2).pdf
        )

)
After Update loop
----------------------------
<pre>Array
(
    [0] => Array
        (
            [REDUNDANT] => No
            [FILE_NAME] => 51894a (2).pdf
        )

)