After the installation process completes, your iMac will automatically reboot into OS X Mountain Lion. For example, choose the hard drive you want to reinstall the operating system on and enter your Apple ID and password when prompted. The OS X Utilities window re-appears.Ĭhoose 'Reinstall OS X' and click 'Continue.' Follow the directions to reinstall OS X Mountain Lion. Open the 'Disk Utility' menu and choose 'Quit Disk Utility' after the system displays the message that the disk has been successfully erased. The time for the process to complete depends on the amount of data on the disk. Click the 'Erase' tab.Ĭlick the 'Format' pop-up list and select 'Mac OS Extended (Journaled).' Enter a name for the hard drive in the Name box and click 'Erase.' The system automatically erases the disk. If you only have one hard drive, it will be the only disk available. If the system does not automatically connect to the Internet, select your wireless network from the Wi-Fi menu to establish a connection.Ĭhoose 'Disk Utility' from the list of options to open the Disk Utility window and click 'Continue.'Ĭhoose the hard drive you want to clear. Select Go > Utilities in the Finder menu bar. Make sure your Mac has enough hard drive space If your Mac doesn’t meet the criteria, you’ll need to choose a version of Windows with lower system requirements.Compare your Mac’s specs for Processor and Memory (RAM) against those listed in the Windows. Release the keys after the OS X Utilities window opens. Mac Make sure the storage device is connected to and mounted on the computer. To use Boot Camp, you’ll need at least 55 GB of free space on your Mac’s hard drive. Press the 'R' and 'Command' keys simultaneously and hold them when the system restarts.

How to clear hard drive on mac