You can modify the PDF template itself to remove or add elements. Some coding experience may be required. The templates are located under /components/invoice_templates/, and the perforated invoice is under /components/invoice_templates/perforated_invoice/. Inside is a file called perforated_invoice_pdf.php which is the one you'd want to edit. You can see x_pos, y_pos and other values that determine alignment.
Invoice templates are carefully crafted to work correctly when there are multiple pages, so you'll want to test any changes you make. If you want to hire us to create a custom PDF invoice template, we are available to do that with a mockup that we can provide a quote from.