MacTex Upgrade from 2015 to 2016
Installing MacTeX 2016 will create a new 2016 directory in /usr/local/texlive/ with all of TeX and friends in it. It will also update all symlinks etc. to point to the new versions. So you can run sudo rm -rf /usr/local/texlive/2015 afterwards to remove the old version. This will lead to some broken links in /Library/TeX but I never bothered with cleaning them up and they won't be used anyway.