Prep for sale or new owner

Question

I have a iMac Core 2 Duo, 7 years old, running Yosemite. I want to give it away to a charity. I need to get all my personal information off first. How do I do this. I already did an erase and reinstall. It doesn't do the trick because when it gets to the install, it needs a WI-FI connection. As soon as I connect to my WI-FI, it finds my name and puts in all my personal information including accounts, passwords, etc. I don't want that to happen. Please, tell me there is a way. I've had several Macs previously, but, don't recall having this problem. It's been seven years since I got a new Mac.  As soon as I put my Apple store account information in, it makes me the Administrator of the iMac. iCloud seems to be the problem. Can't I just get a blank system with no user information? What does one do to sell an iMac to a stranger? Please help.

Answer 1

Hi oduinnin,
Good on you for deciding to give your mac to charity and what a good season to do it in.
The best way to have NO personal data on the device is to completely wipe the device and then NOT touch it, do not add wifi info, just leave it.
The whole purpose of this screen is so that the new owner can configure it to his/her standards. If you do not fill this in all the data will be wiped and no personal info will be visible.
To complelty wipe the device, be aware that all data will be deleted.
I recommend you reading this article as it has all the info you need and steps taken before you sell your device, I will type it below swell.
What to do before selling or giving away your Mac - Apple Support
Step six, is where you get up to and as I stated above, just leave it, do not fill anything in.
If you need help on any of the steps the blue writing is a link that will tell you what to do.
I know your Mac is running Yosemite , but the steps for Mavericks will be extremely similar so you can follow them.
Deauthorize your computer from iTunes, if applicable.
Back up your data using Time Machine or other backup methods for OS X Mavericks or Mountain Lion.
If you use Find My Mac or other iCloud features on this Mac, complete these steps:
Back up your iCloud content.
Choose Apple Menu () > System Preferences, then click iCloud.
Deselect the Find My Mac checkbox.
Sign out of iCloud. When you sign out of iCloud, you're asked whether you want to remove iCloud data from your Mac. Removing iCloud data in this way makes sure that the data isn't also removed from any of your other devices that are using the same iCloud account.
If you're using OS X Mountain Lion v10.8 or later, sign out of iMessage:
In the Messages app, choose Preferences > Accounts.
Select your iMessage account, then click Sign Out.
Reformat your hard drive and reinstall OS X. Follow the appropriate instructions:
OS X Mavericks
OS X Mountain Lion
OS X Lion
After you reformat your hard drive and reinstall OS X, the computer restarts to a Welcome screen and asks you to choose a country or region. If you want to leave the Mac in an out-of-box state, don't continue with the setup of your system. Instead, press Command-Q to shut down the Mac. When the new owner turns on the Mac, the Setup Assistant will guide them through the setup process.
Many Thanks
iBenjamin Crowley