Automatically hide sidebar in preview
I was able to get this to work on 10.11.1 by adding a new key to the Preview.app plist.


  PVPDFSuppressSidebarOnOpening


You can use the defaults write command to do this in Terminal.

cd ~/Library/Containers/com.apple.Preview/Data/Library/Preferences/

defaults write com.apple.Preview PVPDFSuppressSidebarOnOpening true