Though the instructions at Microsoft website is really easy to follow to install Dotnet core 2.0, I realized that the web page does not have instructions that can be easily followed to remove Dotnet core preview 2.

Run the following commands to removed Dotnet core 2.

sudo apt --installed list

sudo apt --installed list | grep "dotnet-sdk"

sudo apt-get remove dotnet-sdk-2.0.0-preview2-006497

dotnet --version