To remove all EXIF, XMP etc. tags from a jpeg file you need no resampling (which, by the way, may give you memory problems). It's just enough to recreate the image, presumably with 100% quality in order not to loose anything. The code is as simple as that:

<?php
    $img = imagecreatefromjpeg ($path);
    imagejpeg ($img, $path, 100);
    imagedestroy ($img);
?>