I know y'all are gonna be wondering how I can even own an iMac without knowing how to do this, or at least figure it out, but I've never really had to restore one of my iMacs before. I have a late 2013 model that I'm selling. It came with restore disks, but there is no disk drive. What do I do to erase and restore this machine? Do I use Time Machine? Thanks for the help.