You can and should delete that file, it was a packaging error to include it.
You are using the pre-compiled deployment file package which is meant for production deployment rather than development in VS.
Note that the presence of that file causes no problem under IIS, it is only because you are opening it as a Web Site in VS that it causes this error because VS assumes it is part of the project as it assumes for all files in a Web Site Project and it is trying to compile everything even though everything is already compiled.
For development I recommend using the source code package which has the VS solution and project files as mojoPortal is really a Web Application Project (not a Web Site Project) with a .csproj file indicating which files are part of the project.
Hope it helps,
Joe