Issues in Xamarin.iOS - Failed to launch the simulator: Could not find file "/Users/_____/Library/Caches/Xamarin/mtbs/builds/...

Clean Visual Studio solution: which can be dome by t manually by removing every bin/obj folder,
On Mac, remove  everything under /Users/<User Name>/Library/Caches/Xamarin/mtbs/builds

In Mac you have two ways of accessing the Go To Folder function from the Mac OS X desktop and Finder:
From the “Go” menu navigate down to “Go to Folder” ….or better yet…
Hit Command+Shift+G from the OS X desktop or a Finder window