I have been thinking about giving my year and half old Mac Pro to a grandson then I would get maybe a Mac Air. Anyway if I do this I would like to take it back to how it was when I first got it (new) from Apple. But, course, with the updated OS. I now have Maverick so I assume I could update it to Yosemite when it comes out?
So the question is how do it clean it out myself?
OS X 10.7 (LION) OR LATER
Thankfully, we no longer have to mess with DVD. With OS X Recovery, we have a built-in set of tools to install OS X, repair and erase your HD, check your internet connection, and restore from Time Machine backup. It's easy to get into OS X Recovery, too:
Restart your Mac and hold down the Command + R keys until the Apple logo appears. From there, you'll see an OS X Utilities window with the aforementioned options listed.
Select Disk Utility and erase your HD, just as instructed to do in the first section of this article. After your HD is erased, resintall OS X. This will install the version of OS X that was first installed on that machine. From there, you can upgrade to the latest version if you choose. To upgrade to 10.10.4, the latest version of Yosemite, you will need to start with at least Snow Leopard 10.6.8.
Apple Support Article on Internet Recovery.
Pre-OS X 10.7
A set of Install / Restore DVDs used to be shipped with all new Macs**, and are most often grey in color. Insert the disc and restart the computer holding down the [C] key. When you boot up of the DVD you will pick your language. Then, from the Utilities menu, select Disk Utility. In there select your hard drive (HD) and use the Erase tab to wipe the drive clean. After you are done, close Disk Utility and continue with the installation from that disk. After you have finished installing, the computer will reboot, taking you back to the original "new Mac" screen.
**Install/Restore DVDs no longer come with new or used Macs. Since Internet Recovery (described above), there is no need for discs, only an internet connection. This works for 10.7 and later. If you're running 10.6 (Snow Leopard) or earlier, you will need an Install / Restore DVD as described above. These discs are available through Apple, PowerMax, and other sources.