Unable to delete a disk image and reclaim hard drive space.
I created a disk image on which to store some stuff, and I now want to get rid of the disk image (which is 115 gigs of storage) and reclaim the hard drive space. I'm running Mac OS X 10.8.3. I have been unable to delete it through disk utility. I can only unmount it or mount it, but the storage space remains with it. I can't get rid of it through the downloads folder either, but if I find it in "volumes" via spotlight, and try to put it in the trash, it tells me "ENN.dmg cannot be thrown away because it can't be deleted." I tried using root user to delete the item and it told me I could not because it belongs to another person. My permissions are "read and write." I've searched all sorts of forums. Can anyone help? Thanks!
MacBook Pro, OS X Mountain Lion