I run SharePoint online in Office 365. I have document content type at site collection level with a few properties. And now when I use it in document library I always get document information panel. I was removing "Custom XML Data" from template. Also in the Document Information Panel settings check box for "show Document Information Panel" is unchecked. Nothing... The DIP is always presented when new document is added. It seems that if I add any single properties to document library DIP will be activated. So how to hide DIP in SharePoint online document library?
Just to pre-empt - there is no solution to this. I have come across the same thing and I've discovered that it will only appear on New documents. If you save the document somewhere or it's saved in the library it will not appear again if that tick box is ticked.