Download a copy of the installer exe from Microsoft:
- DotNetCore.1.0.0.RC2-VS2015Tools.Preview1.exe
- DotNetCore.1.0.0-VS2015Tools.Preview2.exe
- DotNetCore.1.0.0-VS2015Tools.Preview2.0.1.exe
- DotNetCore.1.0.1-VS2015Tools.Preview2.0.2.exe
- DotNetCore.1.0.1-VS2015Tools.Preview2.0.3.exe
- DotNetCore.1.0.1-VS2015Tools.Preview2.0.4.exe
After choose this file when asked. Then you can successfully remove it.