Some time ago I had Windows running on my Mac. I don't remember how I did it but I removed Windows(obvious to me now, incorrectly) but not the partition. I know you're supposed to properly remove it in the Boot Camp Assistant .The option to "Install or Remove or Windows 7 or later version" in the first part of BCA is dimmed and not an option.I can see it but cannot select it. I can still find the Boot Camp disk image and that is has the original space (100MB) I allocated when I first set it up. I want to install Windows again but need to start from a clean slate. How can I completely delete this partition and restore to a single partition OS X volume. Thanks for any help. Yosemite 10.10.2 on a iMac late 2012.