I agree with Ryan, I'd just use some CSS or JS to hide the button as needed. With some additional logic you could make the PDF button hide and show as needed depending on variables as required.
Thanks all for the replies. My first tries didn't work in our Scenario but I will give it another a try and come back to this discussion with more Details.
I cannot confirm this issue. I tested it for the cancel button in preview and in published version, the id of the button always remains the same (even after re-publishing the form). Which control did you try to hide?
Sorry, but I found an issue with this... it works when the form is in Edit mode but the Print PDF button still appears in View mode. Weird. Everything looks the same...
This works for me, but it also removes it from the back end when I use it in a Rich Text widget. I am using the responsive forms and I dont have direct access to the CSS or the formatting rules.