So I have just transfered to a SSD and my 8.1 install was having problems. The problem was: "SkyDrive Sync Engine Host is restarting and explorer.exe kept disappearing" BTW, I don't even use SkyDrive/OneDrive. So I now want to change to a Local account but PC Settings shows the cog icon then the screen goes Blue(not BSOD).

It may happen that your Microsoft account is trying to sync with OneDrive though you are not using it.I shall suggest you to go through the following thread to fix the issue.

http://www.eightforums.com/tutorials/29426-onedrive-integration-windows-8-1-enable-disable.html