In some cases the tool may need the Mac OS X Recovery partition in order to unlock the drive (see question 4). Unplug and plug in the device. Do not boot from the drive. After the device appears in the macOS recovery environment, follow the directions in the article to unlock it with your password. How to Uninstall a Mac from a DVD If the Mac you want to uninstall is installed from a DVD — it must be in your system menu in order to do so. To uninstall a Mac from a DVD : Go to the Mac partition. Click on the Mac partition from which the DVD was originally installed. Unfreeze the Mac. How To Unlock The Recovery Partition On A Mac Go to the menu, and click on Disk Utility. Click Partition. In Partition Tools, click the Partition tab. Scroll down to the Recovery Partition. Select it and click the Unlock button. How To Unlock Mac's Winter Secure Disk Drive This method works for both Mac with Winter Secure Disk drive and those with non-Wintel Secure disks drive. To Unlock The Winter Secure Disk drive: Boot your computer and open the recovery OSX. Open Disk Utility: In Disk Utilities, open the Utilities folder, click Utilities Folder and then double-click Disk Utilities. In the left pane, click on the disk(s) to boot to. Go to the Advanced tab and select the Winter Secure drive (WSS). Click Unlock. At this stage, it may make the computer boot a while, so you may want to open the Terminal. If not, go to Applications > Utilities > Terminal.app. Select “CD” and enter: SU Enter the following command: distil unmounting /dev/disk3s1 Once you hear “Unmounting disk3s1”, you should see some output. At the very end it should display a message for “No disks to unmount”. This is the message we were looking for. Once you've seen this message, enter the following two commands, one at a time: sync && harm (both are “synchronize” commands). Then you can go into the terminal and remove your disk: harm -Y /dev/disk3s1 & After this, you should see that all your data is written safely to the drive.