Don't remove GRUB 2; rEFIt can't boot Linux without the help of GRUB 2 or some other Linux-specific boot loader -- or at least, doing so is awkward and requires advanced skills.
You could, however, install rEFInd, which is an updated version of rEFIt. (rEFIt hasn't been updated in three years.) It's possible for rEFInd to boot a Linux kernel directly, although you'll need to install a suitable EFI filesystem driver and create a configuration file to do so. The procedure would be:
- Install rEFInd under OS X by running the
install.sh script, as described on the rEFInd Web page. Pass the
--alldrivers option to
install.sh to install its filesystem drivers. (You can subsequently remove the ones you're not using if you like; they're stored in
- Reboot. rEFInd should produce a menu with an option to boot Linux via GRUB 2, and probably one or more other options that boot Linux directly (via
vmlinuz-* files). Use the GRUB option; the
vmlinuz-* options won't work yet.
- In Linux, run the
mkrlconf.sh script that comes with rEFInd.
- Reboot and test the Linux boot options -- the ones that launch
- If you can boot Linux via the
vmlinuz-* files, boot to OS X and edit the
/EFI/refind/refind.conf file. Locate the commented-out
scanfor line. Uncomment it and ensure the
hdbios option is not enabled. This will remove the GRUB entry from rEFInd.
- Optionally, in either OS X or Linux, launch
gdisk on your hard disk. (There's an Ubuntu package for
gdisk, or you can download and install the OS X version.) Type
x to enter the experts' menu, type
n to create a new protective MBR, and then type
w to save your changes. This will erase any hybrid MBR that might have existed on the disk, making it safer.
This procedure doesn't actually remove GRUB from your system, but it renders its presence irrelevant. Removing GRUB is possible, but there is effort and risk involved, so IMHO it's not worth doing.