Help removing partition on Macbook Pro

Discussion in 'Mac Basics and Help' started by Aznskill2k, Jun 14, 2015.

  1. Aznskill2k macrumors newbie

    Jun 17, 2011
    Hi all,

    So I am trying to reformat my macbook pro to factory settings, which includes removing partitions and wiping the hdd. I restart my macbook into recovery mode - went into Disk Utility - erased the hdd on both partition(I have 2) - tried to remove 1 of the partition but I got an error message.

    "Partition failed - Partition failed with the error: Couldn't unmount disk."

    I've tried looking this up but the error is pretty general and couldn't find a sure fix. Can anyone help me out? Any advice would be appreciated. Thanks in advance!
  2. c55 macrumors regular


    May 3, 2015
  3. Aznskill2k thread starter macrumors newbie

    Jun 17, 2011
    No, I do not have any external drive connected. Both partition is internal.
  4. MagicBoy macrumors 68040


    May 28, 2006
    Manchester, UK
    You can't delete the partition you are booted from!
  5. Aznskill2k thread starter macrumors newbie

    Jun 17, 2011
    Sorry, not really understanding.

    I only have 1 harddrive on this Macbook called "320.07 GB Hitachi HTS54S.." and on that I have 2 partition called "Macintosh HD" and "04" both having a capacity of ~159GB. So my thought is that I have 2 options of removing the "04" partition.

    1. From the Disk Utility, I select the hd "320.07 GB Hitachi HTS54S.." and from the partition layout I select "04" and click "-", thus removing it and the ~159GB would be allocated to "Macintosh HD".

    2. Repartitioning "320.07 GB Hitachi HTS54S.." into 1 partition and renaming it.

    Both of these options give me the same error message. I am wrong using these approach? If so, how do would you recommend in removing 1 of the partition?
  6. z31fanatic macrumors 6502a


    Mar 7, 2015
    Mukilteo, WA USA
    You are probably booting from the Recovery HD partition of the hard drive.
    Boot into internet recovery by holding down Command + R when you boot. You should be able to erase the entire drive that way.
  7. Weaselboy Moderator


    Staff Member

    Jan 23, 2005
    Do a command-option-r (all three keys at once) boot to Internet recovery. Select your wifi then you will see a spinning globe while the recovery utility downloads. Then start Disk Util and select the drive name itself (Hitachi HTS54S..) at the very top of the left column. Now in the erase tab format the entire disk to Mac OS Extended. Then quit Disk Util and reinstall the OS. This will give you the OS that came from the factory.

    I am assuming here this Mac is on the list at the above link and supports Internet recovery?

    If not, let us know and there is another way using a external USB key.

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6 June 14, 2015