Can't Unmount Bootcamp Partition
I am currently trying to remove the Bootcamp Partition on my iMac. I can successful erase the partition, but if I go to the main hard drive options and select partitions and try to remove it from there, it tells me it can not unmount the disk. I also try to erase the whole hard drive, and it tells me it can't unmount the partition. I also tried booting disk utility from a USB of Yosemite and it still didn't work.
Any ideas on how to fix?