There are several reasons why you might end up with a protected partition you can’t delete on a drive. For example, Macs create 200 MB partitions at the start of an external drive when you set up Time Machine on it.
The Windows DIsk Management tool can’t normally delete these partitions, and you’ll see the “Delete Volume” option grayed out. There’s still a way to remove the partition, but it’s hidden.
First of all, don’t try to do this on your Mac’s internal system drive. Yes, if you use Boot Camp on your Mac and boot into Windows, you’ll see an “EFI System Partition” at the start of your Mac’s internal drive. Leave it alone. This partition is necessary, and you shouldn’t try to remove it. It’s locked for a reason.
However, Mac OS X also creates an EFI System Partition or GPT Protective Partition at the beginning of an external drive when you set up Time Machine. If you’re still using the drive for Time Machine backups, leave that 200 MB partition alone.
The one time when you’ll want to do this is when you were previously using a drive for Time Machine backups, but you’re done with that and want to use it for something else. The 200 MB partition at the beginning of the drive will stubbornly refuse to be deleted, and you’ll have to go beyond the Disk Management tool to delete it.
This process will actually wipe the entire external drive. You can’t simply remove the 200 MB partition and leave any other partitions alone — you’ll be wiping the drive’s contents and starting afresh with a new partition table. If you have any important files on the drive, be sure you have copies of them before you continue. If they’re in Time Machine backup format and you don’t have access to a Mac, you can restore Time Machine backups on Windows.
You can’t actually use the Disk Management tool for most of this, but you can use it for one thing. Note the number of the disk you want to remove the partition from. For example, in the screenshot below, the external drive we want to wipe the partition from is “Disk 2.” It’s actually the third one in the list, but that’s because the first disk is “Disk 0” and the system counts from 0. Remember this number for later.
If you haven’t open the DIsk Management tool yet, you can do it by right-clicking in the bottom-right corner of the screen on Windows 8 or 8.1 and selecting Disk Management. On any version of Windows, you can press Windows Key + R, type diskmgmt.msc into the Run dialog, and press Enter.
You’ll now need to wipe the drive’s partition table entirely. This will remove the 200 MB partition as well as all the other partitions on the disk, erasing the drive. You’ll lose everything on it, and you’ll have to re-partition it later.
To do this, open a Command Prompt window as Administrator. On Windows 8 or 8.1, right-click in the bototm-left corner of your screen and select “Command Prompt (Admin).” On Windows 7, search the Start menu for the “Command Prompt” shortcut, right-click it, and select “Run as Administrator.”
Type the following command and press Enter to run it:
This launches the diskpart command-line utility used for advanced disk partitioning tasks. You’ll see the prompt change to “DISKPART” after you do.
Type the following command to view a list of attached disks on your computer. Note the number of the disk with the 200 MB partition. If you used the Disk Management utility to find this number earlier, it should be the same number:
Type the following command, replacing # with the number of the disk you want to wipe:
select disk #
For example, the disk we want to wipe in the example here is Disk 2. Therefore, we’d type “select disk 2.”
Be very careful that you select the correct disk number. You wouldn’t want to accidentally wipe the wrong disk.
Warning: The below command effectively wipes the drive. You’ll lose all the files on any partition on the drive. Be sure you’ve selected the correct disk number before continuing!
Lastly, run the following command to remove all partition information from the drive. This “cleans” all partition information from the drive, effectively wiping it and turning it into one big, unpartitioned chunk of space:
After the clean command finishes, you’ll be done. All the partitions — including that pesky 200 MB protected partition — will be wiped from the drive. You can leave the diskpart prompt with the following command, and then close the Command Prompt window:
Head back to the Disk Management utility and you’ll see the drive is one big chunk of “Unallocated” space. Right-click the drive’s name and select “Initialize Disk.”
Choose either the GPT or MBR partition style for the disk and it’ll begin to function like any other disk. You can then create the partitions you want on the disk, free from 200 MB partition that appeared stuck to the front of the disk before.
If you ever end up with a drive containing partitions you can’t delete — or if you just want to start the partitioning over from scratch — use the diskpart command to “clean” it.