How do I remove Windows but keep Ubuntu?

Here is a graphical tool to easily remove any OS (Windows, or Ubuntu, or else): OS-Uninstaller

If you have Installed Ubuntu using WUBI then probably trying to remove windows will remove Ubuntu, as Windows installed Ubuntu into its root directory unless you haven't specified a different directory at the installation time.

If you installed Ubuntu in a separate partition you can easily format the drive with Windows. After that remove Windows entry from grub config.

If you use Wubi you can do one of these:

• Copy you user home folder to save most of settings.
• Use OneConf from Maverick.

And reinstall Ubuntu after that.

Considering a more modern system which probably comes with LVM and optionally LUKS full disk encryption, you don't actually need to move or resize partitions the old-fashioned way to get rid of Windows. Instead of the destructive process of shifting the start of a partition—which usually requires a Live USB and risky data moving — you can simply initialize the old Windows space as a new Physical Volume (PV) and add it to your existing Volume Group (VG) and extend Logical Volume (LV) to full VG extents, resizing filesystem at the same time. If you are feeling lucky, you can even do that on HostOS without LiveUSB (although in case of boot errors you will need one either way...).

This method allows you to span your Ubuntu installation across two different physical areas of the disk transparently. If you are new to these concepts, it is helpful to review this conceptual guide to LVM on Ubuntu and this specific walkthrough on extending with LVM (ASCIIart explains more than a thousand words here).

I did it yesterday and can confirm that it is working (with some hiccup at point 2 where I forgot to update crypttab, initramfs and grub)

Before proceeding with the commands below, better read the whole answer first.

1. Wipe Windows and Reallocate

While you can do this via CLI, using a tool like GParted or the Disks utility is often easier for visual confirmation.

• Identify: Run lsblk -f. Look for the ntfs partitions on your NVMe drive. In my case windows partitions were sitting after EFI and before linux boot partition (there were like 3 or 4 partitions for windows — bitlocker partition, some reserved, windows, and some recovery).
• Wipe & Create: Delete the Windows-related partitions (don't delete efi and boot partitions by accident!)
• Format: Create a single new partition in that unallocated space (or two, see point 2.b). Set it as "Unformatted" or "Cleared." Note the device path.

Note on Naming: In the commands below, names like p_WINDOWS_SPACE or p_BOOT are placeholders for your actual partition numbers (e.g., /dev/nvme0n1p3). Always use the specific numbers identified on your system via lsblk.

2. Handling Encryption (The Tradeoff) — optional

If your Ubuntu partition is LUKS encrypted and you want the reclaimed space encrypted as well, it requires some extra work. I tried storing a key on main partition for the second one, but storing the key for the new partition inside your Ubuntu /etc/ folder creates a boot-time deadlock (the system needs the second partition to mount the filesystem, but the key is on that filesystem).

Option A: The Dual Passphrase — TESTED

Simplest setup, but you'll type two passwords at boot.

sudo cryptsetup luksFormat /dev/nvme0n1p_WINDOWS_SPACE
sudo cryptsetup luksOpen /dev/nvme0n1p_WINDOWS_SPACE unwindowsed

Note: It is a bit tedious at boot, but I picked it for simplicity (and because I didn't think of Option B, only encountering the deadlock after trying A).

Option B: The Auxiliary Key Partition (Key Keeper) — NOT TESTED

This uses a small separate LUKS partition to hold keys for the others.

1. Prepare KeyKeeper: You can do that with the Disks GUI program if you select no FS and luks encryption key (I recommand GUI for that). First, create some ~100Mb partition at the beginning of the unallocated space reclaimed from Windows — it will be you keykeeper partition. It's up to you if you do that on the same drive or on a USB to have a "physical key". I don't know the actual needed space, I just eyeballed it

   sudo cryptsetup luksFormat /dev/nvme0n1p_KEYKEEPER
   sudo cryptsetup luksOpen /dev/nvme0n1p_KEYKEEPER keykeeper
   sudo mkfs.ext4 /dev/mapper/keykeeper
   sudo mount /dev/mapper/keykeeper /mnt
   

2. Generate Keys:

   sudo mkdir /mnt/keys
   sudo dd if=/dev/urandom of=/mnt/keys/ubuntu.key bs=512 count=4
   sudo dd if=/dev/urandom of=/mnt/keys/unwindowsed.key bs=512 count=4
   

3. Add Keys:

   sudo cryptsetup luksAddKey /dev/nvme0n1p_UBUNTU_ROOT /mnt/keys/ubuntu.key
   sudo cryptsetup luksAddKey /dev/nvme0n1p_WINDOWS_SPACE /mnt/keys/unwindowsed.key
   

4. Cleanup: sudo umount /mnt (Crucial to unmount this before mounting your OS for chrooting).

3. Extend the LVM

Once the partition is opened as the mapper unwindowsed, you absorb it into your LVM.

1. Initialize the PV:

   sudo pvcreate /dev/mapper/unwindowsed
   

2. Extend VG:

   sudo vgextend ubuntu-vg /dev/mapper/unwindowsed
   

3. Grow LV: The -r flag handles the filesystem resize for you.

   sudo lvextend -r -l +100%FREE /dev/ubuntu-vg/ubuntu-lv
   

Pro-Tip: Use pvs, vgs, and lvs at any time to scan and verify your LVM changes. They give a quick summary of your physical volumes, volume groups, and logical volumes.

4. Making it Permanent (Mount and Chroot) — only if you have encryption

To ensure the system boots, you must update the configuration. If you are doing this from your currently running Ubuntu system, you can skip directly to editing /etc/crypttab. If you are using a Live USB, you must unlock and mount everything first.

Make sure target names are uniform across all steps (previous unwindowsed is my extra_pv). You will see LVM or initramfs warnings which will tell you more otherwise. You could use sudo vgck --updatemetadata to update metadata. On host system main_pv will probably have default name like dm_crypt-0, that's why I like doing it from LiveUSB, because I can name them to something more familiar.

1. Unlock, Mount, and Chroot: — optional, for LiveUSB only, host already has that

   # 1. Open LUKS containers (If encrypted)
   sudo cryptsetup luksOpen /dev/nvme0n1p_UBUNTU_ROOT main_pv
   sudo cryptsetup luksOpen /dev/nvme0n1p_WINDOWS_SPACE extra_pv
   
   # 2. Ensure LVM is active
   sudo vgchange -ay
   
   # 3. Mount Root Logical Volume (this is default name from my ubuntu)
   sudo mount /dev/mapper/ubuntu--vg-ubuntu--lv /mnt
   
   # 4. Mount Boot Partition (where kernels live, e.g., p6)
   sudo mount /dev/nvme0n1p_BOOT /mnt/boot
   
   # 5. Mount EFI Partition (the small FAT32 partition, e.g., p1)
   sudo mount /dev/nvme0n1p_EFI /mnt/boot/efi
   
   # 6. Bind system directories
   for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done
   sudo chroot /mnt
   

2. Update /etc/crypttab: Use the Partition UUID from lsblk -f (found in the crypto_LUKS row), not the LVM member UUID.

   For option 2A skip keykeeper, replace /dev/...:*.key with none and skip keyscript argument:

   keykeeper    UUID=<UUID_of_keykeeper>  none  luks
   ubuntu_main  UUID=<UUID_of_ubuntu>     /dev/mapper/keykeeper:/keys/ubuntu.key  luks,keyscript=/lib/cryptsetup/scripts/passdev
   unwindowsed  UUID=<UUID_of_new_space>  /dev/mapper/keykeeper:/keys/unwindowsed.key  luks,keyscript=/lib/cryptsetup/scripts/passdev
   

   Why passdev? The keyscript=passdev option is critical for Option B. It tells the boot process to wait for a device (the keykeeper mapper) to become available before attempting to read the key file from it. Without it, the system tries to find the file before the partition is even unlocked. It also allows you to have keeper on USB to act as physical key.

3. You may now also delete the old Windows entry from grub — check if there is a /boot/efi/EFI/Microsoft (or similar) and you can rm -rf that directory.

4. Regenerate Boot Files:

   sudo update-initramfs -u -k all
   sudo update-grub
   

5. Exit: exit, then unmount everything.

5. Important Note on Recovery

Always keep a LiveUSB nearby. When playing with crypttab and initramfs, a single typo can result in a "Dependency failed" boot loop or a kernel panic. If the system fails to boot, the LiveUSB is your only way to get back into the Chroot environment to fix your configuration.

After everything I have the following setup:

$ sudo pvs
  PV                   VG        Fmt  Attr PSize    PFree
  /dev/mapper/extra_pv ubuntu-vg lvm2 a--  <476,72g    0
  /dev/mapper/main_pv  ubuntu-vg lvm2 a--  <474,11g    0

$ sudo vgs
  VG        #PV #LV #SN Attr   VSize    VFree
  ubuntu-vg   2   1   0 wz--n- <950,83g    0

$ sudo lvs
  LV        VG        Attr       LSize    Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  ubuntu-lv ubuntu-vg -wi-ao---- <950,83g

$ lsblk -f
NAME                                          FSTYPE      FSVER            LABEL       UUID                                   FSAVAIL FSUSE% MOUNTPOINTS
...
nvme0n1
├─nvme0n1p1                                   vfat        FAT32                        989F-2302                               966,6M     5% /boot/efi
├─nvme0n1p2                                   crypto_LUKS 2                            fc4e684a-e281-478c-901b-6055a8cbf9fc
│ └─extra_pv                                  LVM2_member LVM2 001                     E5zuj5-lW6T-NqU6-r4mc-7iGL-pFaA-SN8BQg
│   └─ubuntu--vg-ubuntu--lv                   ext4        1.0                          f5f0f66e-fea9-48bf-b8a3-33937a51152f      482G    44% /
├─nvme0n1p6                                   ext4        1.0                          a951b0de-8f13-4934-b7f5-57cc955cdda0      1,2G    32% /boot
└─nvme0n1p7                                   crypto_LUKS 2                            143d8c65-ab06-4234-88aa-fa6d5f31aafd
  └─main_pv                                   LVM2_member LVM2 001                     VjEH89-EH3i-xd4o-WlrQ-5PTg-q7fE-dzcea0
    └─ubuntu--vg-ubuntu--lv                   ext4        1.0                          f5f0f66e-fea9-48bf-b8a3-33937a51152f      482G    44% /

# For option 2A
$ cat /etc/crypttab
main_pv         UUID=143d8c65-ab06-4234-88aa-fa6d5f31aafd       none    luks
extra_pv        UUID=fc4e684a-e281-478c-901b-6055a8cbf9fc       none    luks

Also, I went YOLO and did it without any backup, everything went well ¯\_(ツ)_/¯. If I didn't forget to update crypttab/initramfs/grub I would probably have no use of LiveUSB as well.

If you have a partition for Ubuntu and another for Windows you dont have to reinstall Ubuntu. you will start your laptop by Boot from an Ubuntu live USB flash drive, by disks utility format Windows partition, reboot by Ubuntu and open terminal to do thise command:

sudo update-grub 

from now no Windows operating system in your hard disk or boot menu
if (Windows Recovery Environment) in your boot menu you can remove it by Grub-customizer:

sudo apt install grub-customizer

open Grub-customizer and remove Windows Recovery Environment and save.
for full Windows uninstallation you have to delete some files from 1st partition that called System Reserved (may be 500 mg) after that

sudo update-grub

this is other wayes to remove Windows: by Gparted, OS-Uninstaller