Changing GRUB to Bootloader instead of Windows Boot Manager in Dual-Boot System (Windows 10 and Ubuntu)

Changing GRUB Bootloader Instead of Windows Boot Manager in a Dual-Boot System (Windows 10 Ubuntu)

In a dual-boot system with Windows 10 and Ubuntu, the default bootloader is the GRUB bootloader, which allows users to choose the operating system they want to boot into. However, some users may prefer to use the Windows Boot Manager instead of GRUB. This article will guide you through the process of changing the bootloader from GRUB to Windows Boot Manager, and then back to GRUB, in a dual-boot system with Windows 10 and Ubuntu.

Removing Ubuntu and the GRUB Bootloader

If you have decided to remove Ubuntu and the GRUB bootloader from your dual-boot system, you can do so by following these steps:

1. Boot into Windows 10.
2. Press the Windows key + X and select "Disk Management" from the menu.
3. Locate the partition that contains Ubuntu and right-click on it. Select "Delete Volume" to remove the partition.
4. Once the partition has been removed, open a command prompt as an administrator.
5. Type the following command to rebuild the BCD (Boot Configuration Data) store:
   bcdedit /export C:\BCD\_Backup

   bcdedit /create {fwbootmgr} /d "Windows Boot Manager"

   bcdedit /set {fwbootmgr} device partition=C:

   bcdedit /displayorder {current} /addfirst

   bcdedit /timeout 3

These commands will rebuild the BCD store and set the Windows Boot Manager as the default bootloader. Once you have completed these steps, restart your computer, and you will no longer see the GRUB bootloader.

Changing the Bootloader from Windows Boot Manager to GRUB

If you have decided to change the bootloader from Windows Boot Manager to GRUB, you can do so by following these steps:

1. Boot into Windows 10.
2. Open a command prompt as an administrator.
3. Type the following command to open the EFI partition:
   mountvol S: /S

   cd /d S:\EFI\Microsoft\Boot

   bootrec /fixboot

4. Type the following command to rename the Windows Boot Manager:
   ren BCD BCD.bak
5. Boot into Ubuntu.
6. Open a terminal window.
7. Type the following command to install GRUB:
   sudo grub-install /dev/sda
8. Type the following command to update GRUB:
   sudo update-grub
9. Restart your computer, and you will now see the GRUB bootloader instead of the Windows Boot Manager.

• To remove Ubuntu and the GRUB bootloader, delete the Ubuntu partition in Disk Management and rebuild the BCD store using the bcdedit command.
• To change the bootloader from Windows Boot Manager to GRUB, rename the Windows Boot Manager, boot into Ubuntu, and install and update GRUB using the grub-install and update-grub commands.

References

• How to use BCDEdit to modify the Boot Configuration Data in Windows 10
• How to Install and Use GRUB Customizer to Change the GRUB Boot Menu in Ubuntu
• How to Repair GRUB2 When Ubuntu Won't Boot