The .NET Framework 4.7.2 was released in April 2018, and Windows 10 updates automatically installed 4.7.x. Microsoft says that ".NET Framework 4.x versions are in-place updates to earlier versions." You can't downgrade from 4.7.x to 4.6.
While in the Build Note, it says it supports Windows 10 version 1809 (which includes .NET 4.7.x). Does this mean it supports .NET Framework 4.7? If not, when will RAS (and runtime) support .NET Framework 4.7?