# Solved: Can't format because disc won't unmount



## Synt4xError (Jan 23, 2009)

Hello,

I have mountain lion on a macbook pro and I am trying to sell it so I want to install fresh OS X. When I boot into disc recovery by Command + R and choose disk utility I try to select the hard drive and hit erase. I get an error saying the drive cannot be unmounted.

I then decided to just try and install OS X over the existing installation and get the message "drive is locked".

Does anyone have any ideas how I can format my mac and reinstall fresh copy???? IT"S SO ANNOYING! 

Thanks,
Synt4x


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## Headrush (Feb 9, 2005)

Redownload OS X from Mac App Store: http://osxdaily.com/2012/07/26/redownload-os-x-mountain-lion-mac-app-store/

Extract image within Installer and burn DVD using these instructions: http://lifehacker.com/5928780/how-to-burn-os-x-mountain-lion-to-a-dvd-or-usb-flash-drive

Boot off DVD and format and reinstall.


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## Synt4xError (Jan 23, 2009)

I actually just figured it out. I selected the drive below the main one. I don't know how to explain it. Within disk utility in the left pane you have your hard drive and then below it is the partition with your osx on it. I had to select that one instead of the top of the tree. I then right clicked and unmounted the drive. I then was ale to delete the os.

Thanks for the reply though


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