default SHARING folders help

I have Windows SBS 2011 Standard.  In my network there are a bunch of default shared folders: Address, ExchangeOAB, GroupMetrics, netlogon, sysvol, UpdateServicesPackages, WsusContent and WSUSTemp.  I don't really know what these are, and I don't really want anyone in my network to be touching these files, why are they shared and can I unshare them? 

Any help appreciated, Thanks!