Why won't Windows let me delete an EFI partition?

Windows protects EFI (system) partitions from being removed through the normal Disk Management right-click menu so you can't accidentally destroy the partition a system boots from. To delete one you have to drop to the built-in diskpart command-line tool and force the deletion explicitly.

How do I delete an EFI partition on a USB drive in Windows?

Open diskpart (Win + R, type diskpart ), run list disk to find the USB drive, select it with sel disk N , run list partition , select the EFI partition with sel partition N , then run delete partition override . Once it's gone you can format the drive normally in Disk Management.

What does the override in delete partition override do?

The override parameter tells diskpart to delete a protected partition (such as an EFI system partition) that it would otherwise refuse to remove. Without override , the deletion is blocked.

Why does my USB drive have an EFI partition in the first place?

An EFI partition is often created when you use a USB drive to build bootable or recovery media. As soon as that partition exists, Windows treats it as a protected system partition and stops you from deleting it through the usual Disk Management menu.

How do I make sure I'm deleting the right disk in diskpart?

Run list disk and identify the drive by its size. A USB stick is usually far smaller than your internal drives (14 GB in this example) and may show free space. Selecting the wrong disk and deleting its partitions can leave your system inoperable, so confirm the disk number before you select and delete anything.

Format USB drive with EFI partition in Windows

Article Contents

Introduction
Format an EFI Partition
Common Questions

Introduction¶

I seem to collect USB drives. They are handed out at conferences. They are used as recovery media for new machines. They just randomly appear on my desk. I use them to build live Linux CDs, transferring media from one device to another, building recovery media, and generally the things you'd expect a USB drive to be used for. Generally, when I use a USB drive the first thing I do is format it. My USB drives are not for long term storage and I consider anything on them used one time then the drive goes back to the bin for reuse another time.

An annoyance with this, though, is that when I use a drive to build a bootable backup media, often times an EFI partition will be created. As soon as this is created, Windows prevents that partition from being deleted in the future without taking additional steps. I have to go look those up every time because I do it infrequently enough to remember. This is a simple walkthrough of my process to solve this problem

A USB drive with an EFI partition looks like this within the Disk Management tool in Windows

A USB drive with an EFI partition and an unallocated partition

Format an EFI Partition¶

To remove this partition, utilize the built in diskpart tool. Win + R and type in diskpart and allow the application to run.

First you need to find which drive you want to adjust partitions on.

Attention

Ensure you select the correct disk. Failure to do so could result in an inoperable system

Plug the USB drive into the machine and run list disk to see all available disks.

DISKPART> list disk

Disk ###  Status         Size     Free     Dyn  Gpt
--------  -------------  -------  -------  ---  ---
Disk 0    Online         3726 GB  1024 KB        *
Disk 1    Online          931 GB  1024 KB        *
Disk 2    Online           14 GB    14 GB

You can see that I have 3 drives detected. Disk 2 is my USB drive.

Select the disk.

DISKPART> sel disk 2

Disk 2 is now the selected disk.

Then show the partitions on the disk.

DISKPART> list partition

Partition ###  Type              Size     Offset
-------------  ----------------  -------  -------
Partition 1    System            4000 KB   850 KB

There is a single partition - the EFI partition. The rest of the drive is unallocated, as the screenshot above shows. Select this partition. If you have multiple partitions listed, you'll need to determine which is the EFI partition. In my case, since I'm going to be formatting the entire drive anyway, if there were multiple listed I'd select and delete each individual partition.

DISKPART> sel partition 1

Partition 1 is now the selected partition.

Attention

These commands will delete a partition. If you haven't selected the right drive or partition things will break.

Finally, delete the EFI partition

DISKPART> delete partition override
DiskPart successfully deleted the selected partition.

From the disk management tool, you can verify it's gone and format as normal.

All EFI partitions removed

Common Questions

Why won't Windows let me delete an EFI partition?: Windows protects EFI (system) partitions from being removed through the normal Disk Management right-click menu so you can't accidentally destroy the partition a system boots from. To delete one you have to drop to the built-in diskpart command-line tool and force the deletion explicitly.
How do I delete an EFI partition on a USB drive in Windows?: Open diskpart (Win + R, type diskpart), run list disk to find the USB drive, select it with sel disk N, run list partition, select the EFI partition with sel partition N, then run delete partition override. Once it's gone you can format the drive normally in Disk Management.
What does the override in delete partition override do?: The override parameter tells diskpart to delete a protected partition (such as an EFI system partition) that it would otherwise refuse to remove. Without override, the deletion is blocked.
Why does my USB drive have an EFI partition in the first place?: An EFI partition is often created when you use a USB drive to build bootable or recovery media. As soon as that partition exists, Windows treats it as a protected system partition and stops you from deleting it through the usual Disk Management menu.
How do I make sure I'm deleting the right disk in diskpart?: Run list disk and identify the drive by its size. A USB stick is usually far smaller than your internal drives (14 GB in this example) and may show free space. Selecting the wrong disk and deleting its partitions can leave your system inoperable, so confirm the disk number before you select and delete anything.