I baught second hand iMac and having trouble to reset to factory setting Help pls

Question

I baught second hand iMac and having trouble to reset to factory setting Help pls

Answer 1

The previous owner left a Recovery HD partition on the drive. You cannot use it because it will only install a version of OS X that is tied to that persons Apple ID. You cannot use his/her Apple ID nor reinstall his/her copy of OS X. You must start, literally, from scratch.
You can purchase Snow Leopard through the Apple Store: Mac OS X 10.6 Snow Leopard - Apple Store (U.S.). The price is $19.99 plus tax. You will be sent physical media by mail after placing your order.
After you install Snow Leopard you will have to download and install the Mac OS X 10.6.8 Update Combo v1.1 to update Snow Leopard to 10.6.8 and give you access to the App Store. Access to the App Store enables you to download Mavericks if your computer meets the requirements.
     Snow Leopard General Requirements
       1. Mac computer with an Intel processor
       2. 1GB of memory
       3. 5GB of available disk space
       4. DVD drive for installation
       5. Some features require a compatible Internet service provider;
           fees may apply.
       6. Some features require Apple’s iCloud services; fees and
           terms apply.
Clean Install of Snow Leopard
Be sure to make a backup first because the following procedure will erase
the drive and everything on it.
     1. Boot the computer using the Snow Leopard Installer Disc or the Disc 1 that came
         with your computer.  Insert the disc into the optical drive and restart the computer.
         After the chime press and hold down the  "C" key.  Release the key when you see
         a small spinning gear appear below the dark gray Apple logo.
     2. After the installer loads select your language and click on the Continue
         button. When the menu bar appears select Disk Utility from the Utilities menu.
         After DU loads select the hard drive entry from the left side list (mfgr.'s ID and drive
         size.)  Click on the Partition tab in the DU main window.  Set the number of
         partitions to one (1) from the Partitions drop down menu, click on Options button
         and select GUID, click on OK, then set the format type to MacOS Extended
         (Journaled, if supported), then click on the Apply button.
     3. When the formatting has completed quit DU and return to the installer.  Proceed
         with the OS X installation and follow the directions included with the installer.
     4. When the installation has completed your computer will Restart into the Setup
         Assistant. Be sure you configure your initial admin account with the exact same
         username and password that you used on your old drive. After you finish Setup
         Assistant will complete the installation after which you will be running a fresh
         install of OS X.  You can now begin the update process by opening Software
         Update and installing all recommended updates to bring your installation current.
Download and install Mac OS X 10.6.8 Update Combo v1.1.