I needed to uninstall Ubuntu from a Grub dual boot Windows 8.1 / Ubuntu 14.10 computer.

Removing Ubuntu and moving the disk space back to Windows is straightforward and most recipes explain it pretty well. In short: open Disk Management in Windows, delete Ubuntu volumes and partitions then extend the Windows partition.

Restoring Windows boot, however, is another story. Most recipes online require the Windows installation disk or key, but I didn’t have any. The workaround is to create a recovery drive (search for “create a recovery drive”). Boot from the drive, then start the command prompt and write:

bootrec.exe /FixBoot
bootrec.exe /FixMBR
bootrec.exe /FixBoot

That fixed it for me.

I recommend restoring the Windows boot before removing Ubuntu, otherwise you may end up with a computer that doesn’t find any OS.