(PHP 5 >= 5.2.0, PHP 7, PHP 8, PECL zip >= 1.5.0)
ZipArchive::deleteIndex — Delete an entry in the archive using its index
$index): boolDelete an entry in the archive using its index.
indexIndex of the entry to delete.
   Returns true on success or false on failure.
  
Example #1 Delete file from archive using its index
<?php
$zip = new ZipArchive;
if ($zip->open('test.zip') === TRUE) {
    $zip->deleteIndex(2);
    $zip->close();
    echo 'ok';
} else {
    echo 'failed';
}
?>