Two years on and this still hasn't been fixed.  We've had to develop our own software solution for sending invoices without the QuickBooks advert in the emails - what a complete waste of time.

I have left a 1 star review on TrustPilot which I will remove as soon as this has been fixed and I would recommend others do the same: https://uk.trustpilot.com/review/quickbooks.intuit.com