When you install Windows 11 or 10 on your PC's boot drive, the process automatically creates a partition called the EFI System Partition, which stores some critical files the computer needs to read at boot time. The EFI System Partition doesn't take up a lot of space, usually using only a few hundred megabytes (mine was 100MB at the time of writing). Because this partition is needed to boot, Windows doesn't, by default, allow you to delete it.
However, if you take an SSD or hard drive that was once a boot drive and want to completely reformat it to use as a data drive, you may want to get rid of the EFI System Partition so you can have one single, big partition for all of your files. Using the simple instructions below, you can delete the EFI System Partition in Windows 10 or 11. Just make sure you don't do this on your boot drive or you won't be able to boot!
How to Delete the EFI System Partition in Windows
1. Launch Diskpart.
2. Enter list disk to see a list of all the connected drives. The drive number of the drive you want to delete from should be the same as it appears in the Disk Manager app.
3. Enter set disk [Disk Number] where [Disk Number] is the number of the drive you want to delete from.
4. Enter list partition.
5. Enter sel parition [PARTITION NUMBER] to choose the reserved partition you wish to delete.
6. Enter delete partition override.
At this point, the EFI System Partition should be deleted. However, you should confirm by looking at the disk in the Windows Disk Management app (load it by searching for "disk management."). If it still appears, reboot and check again.