Windows 10 doesn't boot after removing Ubuntu: grub black screen

I installed ubuntu-16.04.1-desktop-amd64 on my exteal HDD. I selected to install the grub on that exteal HDD with Ubuntu. When I remove the exteal HDD from my PC, I can't boot into Windows 10 normally, I have to press F11 and select the Windows Boot Loader. If I restart my PC, it loads into a black screen displaying GNU GRUB version ...... Minimal BASH-like editing is supported. For the first word,......

I've tried:

• Windows 10 Recovery to automatically repair the boot: failed. Windows
• 10 Recovery terminal and typing in everything related to bootrec etc for repairing MBR: failed.
• Using Dual Boot Repair from boyans and using the automatic repair: failed.

Doesn't matter what I try, it goes back to that black GNU GRUB screen.

How to fix this?