I have an iMac that I purchased about 6 months ago; OS X 10.9.5. I just noticed on the Finder window in the left-hand column which lists Favorites, Devices, etc. that there is one for Shared. I've not seen this before. And two computers are listed there. I have not done this. Has someone else nearby tried to link with my computer? How could this have happened? I have tried to delete them, but nothing happens. How do I get rid of them? Very puzzled.