SDK Installers will remove previous patch versions

The SDK Installers for Windows will upgrade patch versions in place within the same feature band. This will reduce the number of SDKs that are installed on programmer machines.

Feature bands of the SDK are defined like 3.0.1nn. [Find out more about SDK version numbers](https://docs.microsoft.com/dotnet/core/versions/#versioning-details).

This means when .NET Core SDK 3.0.101 becomes available and is installed, .NET Core SDK 3.0.100 will be removed from the machine if it exists. When .NET Core SDK 3.0.200 becomes available and is installed on the same machine, .NET Core SDK versions like 3.0.101 will not be removed but stay side by side with 3.0.200.

This approach supports use of `global.json` which will roll forward across patch versions, but not feature bands of the SDK. Thus, upgrading via the SDK installer will not result in errors due to a missing SDK. Feature bands also align with side by side Visual Studio installations for those users that install SDKs for Visual Studio use. For example, Visual Studio 15.9 uses .NET Core SDK 2.2.500 but does not support .NET Core SDK 2.2.600.

Find out how to [remove other .NET Core SDK versions here.](https://docs.microsoft.com/dotnet/core/versions/remove-runtime-sdk-versions).