I installed the preview version of dotnet core 2.0 while at Build 2017 and my Mac didn’t like it very much (running OS X 10.1.6). Thankfully the guys manning the Github project have a script to remove all the versions, which allows me to then re-install the correct version. The script can be found here:
https://github.com/dotnet/cli/blob/rel/1.0.0/scripts/obtain/uninstall/dotnet-uninstall-pkgs.sh
