Recently had a requirement to replace an old Server 2008 file server with something a little newer. Rather than attempt an in-place upgrade we decided it was simpler to build the new server (2016 in this instance) afresh and then follow the simple instructions as described by Byron Hay at Spiceworks.
In this case as the old server was a VM we simply disabled the virtual network adapter and shut the guest down before – after a day or two – changing its name and IP address (and removing all shares) before gracefully removing it from the domain.