Yes, you just need to remove the silkscreen layer (and potentially some mechanical layers) from your PDF output settings. Are you using the SmartPDF option? If so, one of the dialog boxes after you begin the SmartPDF output will list the layers to be included. By right clicking on those layers in the PDF settings, you can choose to add, delete, change the order, change the colors, etc for all the layers. If you are using the fabrication/assembly output selection from the file menu, those are configured in your project options under the default prints tab.