How to access webapi controller HttpResponseMessage method

Question

In our project previously they have used web api for xml report generation without any authentication (anonymously).

All the things they have handled through normal asp.net mvc controller and using like " localhost/Abc/WebApi/Controller/Export _ parameters

Localhost-server,
ABC- Project Folder,
WebApi-Folder,
Controller-Controller Name,
Export - Method.

Above are the details to access xml report using URL.

But for only one thing they have used Api controller.

Like Below,

public virtual HttpResponseMessage ManExport(string ABC, string product, string Release, bool includeInheritedData = false)
{

}
How to access this webApi controller in URL? like normal controller?

If its normal controller we can access it via actionresult method name but how to access with HTTPResponsemessage in the URL.