The only way I have found to do this is to save it to PDF, edit the PDF, and delete the button and the text that is on top of the button. Very inefficient and not a good process for doing business. But it's a workaround until the (hopefully) fix it. I email customers but there are some that we want to physically mail an invoice and it looks very unprofessional to have a pay and review button on a piece of paper... 

Edit: I went in and looked again after my post and they have now added the feature to do this. In the edit invoice screen, click on Manage -> Design -> Payment Link -> toggle the "Add payment link to PDF" off. If you want it to default to this, try following the suggestions above. I haven't tried them since I don't want all of them like this but it looks like some have had success with it.