How do I completely clean out/reset/reformat/whatever my Macintosh? I’m talking a deep cleanse here.
I’m willing to look at any free software that may aid in this.
Boot the OS X disc that came with your computer, and in the menu bar, go to
Utilities -> Disk Utility and select your disk in the left column (e.g.
500GB Hitachi...). Click on the
Erase tab at the top, and select
Max OS Extended (Journaled) from the drop-down menu. Title your disk (if you want, or leave it as Macintosh HD), and click
Erase. Quit disk utility (command + q) and continue with the OS X install as normal.