Unable to format/partition hard drive
So I've recently decided my previous three partitions, including a partition with windows on, are not needed so backed up the files and am trying to simply format the whole hard disk. It lets me format two of the old partitions, but not the one with windows OS on it (erase is greyed out).
In terminal I tried
diskutil reformat /dev/disk2
but get
disk2 does not appear to have a valid file system format
Usage: diskutil reformat MountPoint|DiskIdentifier|DeviceNode
Completely erase an existing volume with the same name and format as the
original. Ownership of the affected disk is required.
You cannot erase the boot volume, nor can you reformat any device which
does not have a valid file system (instead use diskutil eraseVolume).
The partition table is master boot record for the HDD. That's about as far as I can get. Anyone?
MacBook Pro, OS X Mavericks (10.9.5)