Can you please confirm if CA Release Automation requires .NET application and or Visual Studio.
Release : 6.6, 6.7 or higher
Component : CA RELEASE AUTOMATION RELEASE OPERATIONS CENTER
As per verification in system requirements of overall RA product and I don't see dependency on .Net/Visual Studio code.
With the context you provided, I believe that your windows servers may be having those possibly due to below cause.
1: The servers may be having IIS enabled, whose pre-requisite is .NET Framework and VS C++ redistributable
2: The server may be having PowerShell, whose also lead to availability of .NET Framework.
From RA end I don't see any dependency on .NET Framework or Visual Studio, however it looks like they are on server due to some other windows component with them as pre-requisite.