For those of you that have tried out Linux the install-it-for-real way (meaning not virtually or using Wubi), the GRUB boot loader is installed.

Side note: There’s also LILO, but the one I see more often than not for most Linux distros, namely Ubuntu, is GRUB.

If using Microsoft software to remove GRUB from a hard drive, you would either use FDISK or fixmbr.

FDISK

This is commonly known as "the DOS way".

1. Physically disconnect all hard drives from your PC.
2. Connect the hard drive you want to remove GRUB from.
3. Boot from a Windows 98 CD.
4. Exit to a command prompt.
5. Run FDISK /MBR
6. Shut off the computer.
7. Restart the computer. There should be no "GRUB Error 17" at this point but rather just a standard notice that states there’s no OS on the drive and/or no boot media present depending on your BIOS notices.

The /MBR flag means Master Boot Record and is an undocumented part of the FDISK program; this is why you don’t see any documentation on it when you run FDISK /?

fixmbr

This is a repair utility that’s available via the Windows XP CD.

Follow steps 1 and 2 for FDISK above, then boot the computer with the XP CD. Choose to go to the Recovery Console and run fixmbr. You do not need to specify a specific hard disk if the drive you want to remove GRUB from is the only one physically connected to the computer. Follow steps 6 and 7 for FDISK above after running fixmbr.

Is there a way to remove GRUB from a hard drive from within Windows?

Yes – but only on a secondary drive (meaning not the boot drive). You can use Partition Wizard. The "Home" version is free. It will run in Windows 2000, XP, Vista and 7 and "knows" how to handle Linux files systems and boot loaders – including how to wipe them. It even supports RAID drives.

Note: Linux file systems are only supported up to ext3, so if you have a newer ext4, Partition Wizard doesn’t support that yet. However I’m sure it will in future release versions.

For those of you with external USB hard drives, you will really like Partition Wizard because it allows you to do basically anything with the partitions on the drive all from within Windows. Resize them, wipe the whole thing and start over, etc.

I have to tack a small disclaimer here: Obviously you should be very careful when modifying boot records and/or partitions, because with the wrong click you can make all the data on the drive completely inaccessible. It is suggested you only modify boot records/partitions on a drive where you absolutely don’t care if the data on it is lost.