I booted a Ubuntu 16.04 Live USB and installed onto an external HDD. In the partitioning step I had it install grub to the external HDD, not my internal Windows 10 HDD. But when I rebooted the computer, it boots to a grub command line.
In side the UEFI, there is still a Window Boot Manger option, plus 2 Ubuntu boot options. I can still boot to Win10 through the WBM, but the 2 Ubuntu options do nothing.
How can I remove all traces of Grub and the 2 Ubuntu boot options from the Win10 HDD?