I did exactly as the manual said (after the typo “iaStorAV” had been fixed), but the system still goes wrong and Windows cannot normally boot (exactly the same as in the picture … pity!)
Then I tried the following steps in the manual. I finished using “diskpart”. But any of the “bcdedit” commands doesn’t work on my computer. It said it could not find the file. I didn’t know what file it’s talking about. So I moved on.
And finally the “Bcdboot” stage. Still the “ren BCD BCD.bak” could not find corresponding files. But the “bcdboot” command worked, and the boot files are successfully created. Unfortunately, windows could not boot in the end 
a blue screen …
------------------- after several minutes ------------------
THANK GOD!! Before I finished downloading the win10 System installer, I retried changing my computer’s storage controller protocol from AHCI to RST and reboot. It worked! And I can now use my computer again!
No more ubuntu on this computer … . Luckily I have another computer where I installed Ubuntu 18 successfully.