Windows 10: Revert dual boot/GRUB - help needed

Hi. At the outset, I am new to dual boot so it is likely I have made some mistakes here. Please bear with me.

I have an Ideapad with preinstalled Windows 10 and UEFI. I installed Ubuntu in a separate partition and installed the boot loader to the EFI partition. All worked well, I was able to dual boot Ubuntu and Windows using GRUB. A while later I decided to remove the dual boot and go back to a single boot Windows 10. I deleted the Ubuntu partition and now I am trying to restore the original Windows boot loader/remove GRUB and all Ubuntu remnants from the system and get back to the original setup.

What is the best way to do this? I tried looking up some links online but they all refer to a tool called bcdboot and after some research I think this tool is not valid for UEFI?

Appreciate any advice or (even better) detailed steps. Thank you.

submitted by /u/pewiro1580
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:)

 

Dual boot not reaching windows, but grub detects it

After you move disks, partitions (eventually add/delete partitions) the principle for fixing boot is always:

1. Fix Windows boot
   
2. Fix GRUB boot
   

in that order.

Boot configuration should be such that Windows must be able to boot alone without the help of any other boot loader/manager!

What does Windows 10/8/7 use for booting with BIOS firmware (and MBR style disk):

1. MBR
   
2. PBR of active partition
   
3. bootmgr on active partition
   
4. BCD on active partition
   

in that order.

A Windows 10 installation/repair USB/DVD can be used to fix boot in this case.

See fix Windows 10/8/7 boot for help on repair steps.

For fixing GRUB you can use a Linux live CD/USB.

Be aware that after a Windows 10 version upgrade/update it possible that Windows will overwrite MBR (overwrite GRUB boot code in MBR)!

Suggestion - use Windows boot manager to dual-boot Windows and Linux.

 

dual boot menu and gnu grub

in windows 10 i got only one os (that is win 10 ) and i still see dual boot menu and when i open my pc it starts from gnu grub please help

 

dual boot menu and gnu grub

Is GRUB installed to another partition where you have or had Linux? If so you should be able to delete that partition and it may be easier to rebuild the BCD. But if GRUB is installed in the System or Windows partitions then it may be hard to overwrite.
This is a reason it's best to follow this procedure to Dual Boot so you know how to get rid of it properly:

https://www.groovypost.com/howto/dual-boot-wind...

When rebuilding the BCD remember that the boot files are not necessarily on the C partition but will more likely be on the System Reserved or EFI System. So you can determine this with Diskpart and if necessary Assign a letter so you can export the BCD first
which is often necessary to have it work.