Go into advanced sharing settings.
Homegroup conections, set to ->
"Use user accounts and passwords to connect to other computers". This will turn off the homegroup.
Then, subsequently, turn off network discovery and turn off file and printer sharing.
Nothing should be shared then.
Actually I do tend to set things up in that way but the system still tends to set up a network location and every so often a homegroup icon appears on the desktop.
When I bought the PC it was running Windows 7 and it came with a £15.00 upgrade to Windows 8 Pro which then upgraded itself to Windows 8.1 Pro and It could be that experimented with the file sharing options at an earlier time but I have carried out clean installs from Windows 7 upwards and it makes no difference.
It some ways it would be nice to be able to set up some carefully controlled file sharing in the way that it could be with Windows XP but it seems to me that from windows 7 onwards Microsoft have been determined to share almost everything and security may be taking a back seat.
For example; my ASUS DSL-AC68U router has a USB port and it would be nice to connect my USB printer to the USB port of that router but that would probably require some sharing.
The theory is that in the worse scenario the files should only be available on the home network and even then they should only be available via a password but my concern is that it is not that secure. - I do know that prior to our house move when I also had an older Windows XP computer on the network and my sons computer, (which uses Windows 7), my son,s computer could not access the files but see them but when my old Windows XP computer was switched on it could see and access the files on my Windows 8.1 computer without problem.
I am definitely not a computer whiz but I can usually set things up reasonably well and I have always used a reasonable internet security package, (Previously I used the paid for version of AVG Internet Security and I recently changed to BT Netplus/McAffee package that is supplied free with BT Infinity customers).
In Windows 8 onwards the Apps seem to do an awful lot behind the scenes and it is much harder to see what is going on.
The 64,000 Dollar Question is; what file access security settings can be used to make the computer user files totally private if some file sharing was allowed?
BT Infinity