Run the Boot Camp assistant and it will automatically start the removal process after some prompts.
You will need to use something like VMWare Converter to create a VM first if you want to keep the Windows Installation. You can then convert this to a Parallels VM.
Warning: Please be sure you have a good idea of what exactly is happening before following any advice that I write here. This may be risky! Please do a bit more Googling before pressing ENTER on a Linux terminal. :)
I had this same problem after I removed a partition containing Windows 7 using Disk Utility. The problem in my case was that the Windows 7 partition was removed, but the Windows boot loader installed on the Master Boot Record (often denoted MBR) remained. To remove it, use dd as in the example below.
EXAMPLE: If your Windows boot loader is installed on the MBR of your sda drive, from a Linux terminal run:
(WARNING, DON'T BLINDLY TYPE THIS WITHOUT READING THE DESCRIPTION ABOVE:) sudo dd if=/dev/zero of=/dev/sda bs=440 count=1
The dd command is also helpful if you have an extra GRUB boot loader installed somewhere. For example, I mistakenly installed a GRUB boot loader on my second hard drive both in the second hard drive's MBR and in the second hard drive's first partition. rEFIt listed both of the boot loaders, even though only the one installed on the second hard drive's MBR worked. So to remove the extra GRUB boot loader on the first partition of the second drive I also used dd as below.
EXAMPLE 2: If you have an extra GRUB boot loader installed on a partition, in this example partition sdb1, from a Linux terminal run dd as in the example below. (Notice the "of=..." changed and the "bs=..." changed from the first example.)
(WARNING, DON'T BLINDLY TYPE THIS WITHOUT READING THE DESCRIPTION ABOVE:) sudo dd if=/dev/zero of=/dev/sdb1 bs=446 count=1
I know this is an old question, but it was never really answered. I hope this helps many people who were led to this page while searching for this problem. God bless!
Use Disk Utility to do it. Select your partition and hit the "New Image" button. In the Save sheet that pops up, set the Image Format to "DVD/CD Master". Disk Utility will suggest a filename extension of
.cdrfor the resulting disk image, but just change it to
.iso. They're just different names for the same thing.