Warning on Unallocated Space
Deleting Ubuntu partitions creates unallocated space. If not properly handled, this space may become inaccessible or lead to filesystem corruption. Tools like `gparted` or `disks` allow resizing but require caution when moving partitions.

Manual Partition Deletion Using Linux Tools

Using GNOME Disks or GParted
1. Launch GParted:
```bash
sudo gparted
```
or open Disks (GNOME) and select the target disk.

2. Unmount Ubuntu Partitions:
Right-click each Ubuntu partition (e.g., `/`, `/home`, `swap`) and select Unmount. Skip the ESP if Windows is the sole remaining OS.

3. Delete Partitions:
Right-click each Ubuntu partition in reverse order (e.g., delete `/home` before `/` to avoid dependency errors) and choose Delete. Confirm the action.

4. Handle Unallocated Space:

5. Update Bootloader (UEFI Systems):
Reboot into Windows and run:
```cmd
bcdedit /set {bootmgr} path \EFI\Microsoft\Boot\bootmgfw.efi
```
This ensures the Windows Boot Manager is the default.

Using Command Line (`fdisk`, `parted`)
1. Delete Partitions:
```bash
sudo fdisk /dev/sdX # Replace X with the disk (e.g., sda)
```
In the `fdisk` prompt, use `d` to delete partitions by number. Confirm each deletion.

2. Wipe Partition Tables (Optional):
For a clean slate, use:
```bash
sudo wipefs -a /dev/sdX
```
Warning: This erases all signatures on the disk; use only if necessary.

3. Format Unallocated Space:
```bash
sudo mkfs.ntfs -f /dev/sdXY # For NTFS (Windows)
sudo mkfs.fat -F32 /dev/sdXY # For FAT32 (ESP)
```

Removing Ubuntu via Windows Disk Management

Prerequisites

Step-by-Step Partition Deletion
1. Open Disk Management:
Press `Win + X` > Disk Management or search for `diskmgmt.msc`.

2. Shrink the Windows Partition:

3. Delete Ubuntu Partitions:

4. Format Unallocated Space:

5. Clean Orphaned UEFI Entries:
Open Command Prompt as Administrator and run:
```cmd
bcdedit /deletevalue {bootmgr} path
bcdedit /delete {current} # Removes redundant entries
```
Verify with:
```cmd
bcdedit /enum
```

Risks of Improper Deletion

Forcefully deleting Ubuntu partitions without adjusting the bootloader can result in:

Broken Windows Boot: Missing or corrupted EFI entries prevent Windows from loading.

Orphaned GRUB Configurations: Leftover GRUB files in the ESP may cause boot loops or errors like "No bootable device."

Data Corruption: Improperly formatted unallocated space can render adjacent partitions inaccessible.

Lost Recovery Options: UEFI systems may retain old boot entries, complicating future repairs.

After deleting Ubuntu partitions and shrinking `C:` to 300GB, the remaining 200GB can be formatted as NTFS for Windows use. The ESP (if separate) must be reformatted to FAT32 and repopulated with Windows boot files.

Automated Tools for Removing Ubuntu from Dual-Boot Systems

Comparison of Automated Tools for Ubuntu Removal

Key Considerations for Tool Selection:

GRUB Entry Removal: Tools must identify and purge Ubuntu-specific GRUB entries without disrupting the primary OS (e.g., Windows).

UEFI vs. Legacy BIOS Support: UEFI systems require EFI partition manipulation, while Legacy BIOS systems rely on MBR modifications.

Side Effects: Potential risks include corrupted boot records, unintended partition deletions, or failure to restore the original bootloader.

1. EasyUEFI
   EasyUEFI specializes in UEFI-based systems, offering a graphical interface to manage EFI boot entries directly. It excels in removing Ubuntu EFI executables (e.g., `grubx64.efi`) and restoring default Windows boot options.
   • GRUB Entry Removal: Detects and deletes Ubuntu EFI entries via the "Boot Entry Manager" but may require manual confirmation for ambiguous entries.
   • UEFI/Legacy Support: Optimized for UEFI systems; Legacy BIOS support is limited to MBR boot record adjustments (less precise).
   • Side Effects: Rare but possible if misconfigured—may overwrite critical EFI files if the "Restore Default" option is misused. Always back up the EFI partition before proceeding.
   • Use Case: Ideal for UEFI systems where Ubuntu’s EFI boot entry persists after uninstallation.
2. Boot-Repair (Standalone Version)
   Boot-Repair is a Linux-based tool designed to repair bootloaders, including GRUB. Its standalone version (accessible via a Windows-compatible ISO) can reconfigure bootloaders without requiring Ubuntu to be installed.
   • GRUB Entry Removal: Automatically detects and removes Ubuntu GRUB entries, replacing them with Windows Boot Manager (for UEFI) or the Windows MBR (for Legacy).
   • UEFI/Legacy Support: Fully compatible with both UEFI and Legacy BIOS systems, with dedicated repair options for each.
   • Side Effects: May fail to restore the original Windows bootloader if the system’s EFI partition is corrupted. Requires administrative privileges and may log errors during execution.
   • Use Case: Suitable for systems where GRUB overwrites the Windows bootloader or where Ubuntu’s traces remain in the boot order.
3. Ubuntu Live USB’s `boot-repair`
   The `boot-repair` utility included in Ubuntu Live USB environments provides a more interactive approach, allowing users to manually select bootloader configurations.
   • GRUB Entry Removal: Offers granular control to remove Ubuntu GRUB entries and reinstall Windows Boot Manager. Requires manual selection of the "Recommended repair" option.
   • UEFI/Legacy Support: Works on both UEFI and Legacy systems but relies on the Live USB’s ability to access the host system’s partitions.
   • Side Effects: Risk of data loss if partitions are incorrectly identified during the "Backup and Reinstall" process. Always verify partition mappings before proceeding.
   • Use Case: Best for users comfortable with Linux environments who need fine-grained control over bootloader adjustments.

Automated Script for UEFI-Based Ubuntu Removal

Prerequisites:

Run as Administrator (Windows) or with `sudo` (Linux).

Ensure `efibootmgr` and `grub-probe` are installed (Linux) or use Windows Subsystem for Linux (WSL) for cross-platform execution.

Backup the EFI partition (`\\EFI\\Microsoft\\Boot`) before execution.

#!/bin/bash

Script to remove Ubuntu EFI boot entries and verify Windows Boot Manager integrity
Requires: efibootmgr (Linux), grub-probe (Linux), or WSL with admin rights (Windows)
# Step 1: List all EFI boot entries to identify Ubuntu-related entries

echo "[INFO] Listing current EFI boot entries..."

efibootmgr -v | grep -i "ubuntu\|grub\|linux" || echo "[INFO] No Ubuntu entries found."
# Step 2: Delete Ubuntu EFI entries (replace 'XXXX' with actual BootXXXX entries)

Example: Delete entries with names containing "ubuntu" or "grub"
for entry in $(efibootmgr -v | grep -i "ubuntu\|grub" | awk '{print $1}'); do

    echo "[ACTION] Deleting EFI entry: $entry"

    efibootmgr -b "$entry" -B || echo "[ERROR] Failed to delete $entry"

done
# Step 3: Verify Windows Boot Manager is set as default

echo "[INFO] Setting Windows Boot Manager (Boot0000) as default..."

efibootmgr -o 0000,0001,0002,0003 || echo "[ERROR] Failed to set default boot order."
# Step 4: Probe for Windows EFI partition and validate Boot Manager

echo "[INFO] Probing Windows EFI partition..."

WINDOWS_EFI=$(grub-probe --target=fs /boot/efi | grep -i "vfat\|fat32")

if [ -z "$WINDOWS_EFI" ]; then

    echo "[ERROR] Windows EFI partition not found. Aborting."

    exit 1

fi
# Step 5: Check for critical EFI files (Windows Boot Manager)

echo "[INFO] Verifying Windows Boot Manager files..."

if [ -f "$WINDOWS_EFI/EFI/Microsoft/Boot/bootmgfw.efi" ]; then

    echo "[SUCCESS] Windows Boot Manager verified."

else

    echo "[ERROR] bootmgfw.efi missing. Manual recovery required."

    exit 1

fi
# Step 6: Log cleanup report

echo "[REPORT] Ubuntu removal completed. Verify boot order in UEFI settings."

efibootmgr -v > /tmp/efi_cleanup_report.txt

echo "[INFO] Report saved to /tmp/efi_cleanup_report.txt"

Third-Party Utilities for Dual-Boot Cleanup

General Safety Notes:

Always back up critical partitions (e.g., EFI, Windows recovery) before using third-party tools.

Non-destructive modes may still require manual confirmation for critical operations.

Verify bootloader integrity post-cleanup using `bcdedit` (Windows) or `efibootmgr` (Linux).