The only way to remove the pay now button and scan code is to save the invoice as a PDF and then go into your PDF and edit it (remove those items) then re-save and then attach to an email.  This requires an old school manual way to do it but is worth not confusing or derring customers away and complying with being forced to advertise for intuits banking products.  I definitely would not recommend QB any longer, back in the day- sure but now days definitely not!