How can I remove bcdedit's GRUB completely?

I added GRUB to my Ubuntu installation's disk by bcdedit /set {bootmgr} path \EFI\ubuntu\grubx64.efi.

Then, I removed Ubuntu from my disk and deleted the "ubuntu" file in the EFI.

Every time I boot my computer, I get a message: fail to open EFI.... and then my computer boots into Windows 8.

2 Answers

There are several ways to do what you want:

• You can use the same bcdedit command in Windows, but instead of \EFI\ubuntu\grubx64.efi, you can specify \EFI\Microsoft\Boot\bootmgfw.efi.
• You can use the EasyUEFI program in Windows to manage the EFI boot entries in a GUI way. This is likely to be less error-prone that bcdedit. Move the Windows entry to the top of the list and/or delete the Ubuntu entry.
• You can boot an Ubuntu live disk and use efibootmgr to delete the Ubuntu entry and/or move the Windows entry to the top of the list. Type sudo efibootmgr (or sudo efibootmgr -v to see more details) to see the list of options; then use the -b #### -B option to delete one, or -o ####[,####[,...]] to change the boot order. (#### is a four-digit hexadecimal number associated with a boot entry.) Type man efibootmgr for more documentation on this command.
• Many EFIs provide a way to manage boot entries in their own user interfaces. Details vary greatly from one system to another, though.

Another simple way to fix this from Windows 8/10 is using admin command prompt:

bcdboot c:\windows

To remove remnants of grub completely you have to clean up EFI system partition(ESP). This can be done easily using Dual-boot Repair 10 as it mapps ESP automatically to drive Z:(or another free drive letter). Use for example "Backup BCD" dialog to browse z:\EFI and delete "ubuntu" folder.