Why is VS 2015 community auto-installing during compile-time when I have VS 2015 Professional already installed

I have had VS 2015 installed in Win 10 for a couple years, however, all of sudden VS 2015 community started auto-installing for no explained reason during a typical compile. What do you suppose is going on? Each time, I have killed the install -- since I don't need community installed. How can I kill this from happening? - it's annoying.