To remove all images from a document page.

$doc = new PDFDoc($filename);
$page = $doc->GetPage(1);

$writer = new ElementWriter();
$reader = new ElementReader();
$reader->Begin($page);
$writer->Begin($page, ElementWriter::e_replacement, false);

while (($element = $reader->Next()) != null) 	// Read page contents
{
    switch ($element->GetType())
    {		
        case Element::e_image: 
        case Element::e_inline_image: 
            // remove all images by skipping them			
            break;
        default:
        $writer->WriteElement($element);
    }
}

$writer->End();
$reader->End();

PDF Editor (Programmatic)
Full code sample which strips all images from the page and changes text color to blue.