ASP NET MVC 5 Delete File From Server

use Request.MapPath

string fullPath = Request.MapPath("~/Images/Cakes/" + photoName);
if (System.IO.File.Exists(fullPath))
{
   System.IO.File.Delete(fullPath);
}

File, as you're using it, is ambiguous, hence the "squiggly line". The IDE can't resolve which you mean;

System.Web.Mvc.Controller.File()

or

System.IO.File

Use a fully-qualified name when trying to use the File API within an MVC controller.