I have started upgrading to ASP.NET Core RC2, following the instructions provided. However, I'm confused - it seems as though there was no mention of uninstalling DNX or any of the other CLIs (DNVM and DNU). Does that need to be uninstalled, or does RC2 rely on it somehow?
After following the instructions and rebooting, I still have a dnx.exe in my task manager and a .dnx folder even though I deleted it as part of the upgrade. I can literally delete the entire .dnx directory, runtime and all - and after opening Visual Studio it comes back after the dotnet CLI starts.
The .NET Core RC2 and ASP.NET Core does not rely on DNX at all. Afair there is a compatibility layer during the last month, but that should be gone as well.
If your projects build with RC2, then you can safely uninstall all ASP.NET 5 tooling (dnx, dnvm, ...) and delete their caches. Also deleting the nuget cache does not harm and reduce space (since the actual parts will restore on next opportunity).
Your problem with Visual Studio is that most probably the VS tooling for ASP.NET is still there. I had problems uninstalling them, but once done, you can use Visual Studio without encountering DNX or "ASP.NET 5" projects.