Go Back To Windows 10 from Ubuntu 20.04 [duplicate]

I have absolutely no experience with Linux, and I desperately need to get my computer back up and running again with Windows.

How do I remove Ubuntu and reinstall Windows?

Editor's note: many of the answers are about removing Ubuntu from dual-boot but keeping Windows (which is a bit complicated), while other answers are about removing Ubuntu from single-boot (which is easy: basically just format the disk while installing Windows). The question as written is ambiguous between dual-boot or single-boot.

If you have a single-boot system with only Ubuntu installed, you can install Windows directly and override Ubuntu completely. To remove Ubuntu from a Ubuntu/Windows dual boot system, you will first need to replace the GRUB bootloader with the Windows bootloader. Then, you would need to remove the Ubuntu partitions.

The first step can be done with a Windows Recovery DVD/Installation DVD or a Ubuntu Live DVD. If you have a newer Dell laptop (such as the Dell Inspiron), you would need to do so by changing the boot sequence in the UEFI settings, which will be discussed later.

Using Windows Recovery or Installation Media

If you don't have a Windows recovery or installation media, you can download official ISO files for Windows 10, Windows 8, or Windows 7 from the Microsoft Download Center and burn them on a DVD or a USB drive. Windows will only install as an evaluation copy for 30 days without a genuine product key.

Grab a Windows recovery or installation media and boot from it. You should see this or a similar screen on a recovery media.

You should see this on an installation media. Click "Repair your computer" and you should see a screen like the first image.
Open the Command Prompt, then type bootrec /fixmbr into the Command Prompt.
Reboot and boot into Windows. Then follow the steps below to remove the Ubuntu partitions.

Using a Ubuntu Live DVD and Boot Repair

If you don't have a Windows recovery CD or you are constrained to download and burn the ISO files mentioned before, you can use Boot-repair. It is a tool that fixes most boot problems(Windows or Ubuntu). I suggest using a Windows CD if possible.

Boot from a Ubuntu Live DVD or USB

Type these lines in the terminal one line at a time.

sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install boot-repair

Search for Boot-Repair in the Dash and launch it.

To fix your computer with Boot-repair, simply click the "Recommended Repair" button. Then follow the steps below to remove the Ubuntu Partitions.

Changing the Boot Sequence in the UEFI settings of a Dell computer

Newer Dell laptops like the Dell Inspiron requires the bootloader order to be changed directly in the UEFI settings. This can be done with the following steps.

Pressing F12 when the Dell logo appears.
Go to General → Boot Sequence. Under the Boot Sequence section, select Ubuntu, then click Delete Boot Option.
Reboot your computer.

Deleting Ubuntu Partitions

After the previous steps, your computer should boot directly into Windows.

Go to Start, right click Computer, then select Manage. Then select Disk Management from the sidebar.
Right-click your Ubuntu partitions and select "Delete". Check before you delete!
Then, right-click the partition that is on the Left of the free space. Select "Extend Volume". Go through the Wizard and Finish it.
Done!

Note from Tanner: If you are using an extended partition, you might have to remove the big extended partition to make the space unallocated.

Boot a live CD/DVD/USB with Ubuntu
Choose "Try Ubuntu"
Download and install OS-Uninstaller.
Start the software and select what operating system you want to uninstall.
Apply
When all is over, reboot your computer, and voila, only Windows is on your computer or of course no OS!

First download bootsect.exe into the Download directory.

press the windows key, type cmd.exe and on the result (The command prompt) start it as an "Administrator" by right clicking on the cmd icon, and select Run as Administrator.

In the new cmd.exe window, cd to your download directory. for example cd C:\Users\Lalu Patel\Downloads. _assuming your user name is "Lalu Patel".

Then enter this command. bootsect.exe /nt60 ALL /force /mbr. Restart your system to see that, Windows is automatically loading without grub.

Then in Windows

Open the Control Panel (All Items view), and click on the Administrative Tools icon. then close the Control Panel window
Click on Computer Management in Administrative Tools, then close the Administrative Tools window.
In the left pane under Storage, click on Disk Management. see this.
Select the the partition with unknown type. it is the Ubuntu partition. Right Click -> Delete partition.
Now the former Ubuntu partition becomes an unallocated space.
Select the left partition of the new unallocated space.
Right click on the partition -> click on Extend Volume.
Click on the Next button.
Type in how many MB (1 GB = 1024 MB) you want to use from the unallocated space to extend the selected partition (step 5) into, then click on the Next button.see this.

Note: If you want to use all of the unallocated space to extend into, then type in the maximum available space shown for the unallocated space.
Click on the Finish button. You're done.

Source: bootsect, disk management

If you don't have a Windows CD and deleted the Ubuntu partition

Scenario:

You want to remove Ubuntu, and deleted the Ubuntu partition from within another OS. Now, your computer wont boot ("no such partition") and you lack a Windows Recovery CD to fix it.

Create a Ubuntu LiveCD/USB.
Boot from your Ubuntu LiveCD/USB by selecting it in the BIOS boot options.
Once Ubuntu loads, open a Terminal (Ctrl+Alt+T), and run these commands:
```
sudo apt-get install lilo
sudo lilo -M /dev/sda
```
Note: you may have to replace /dev/sda with the main hard drive you installed Ubuntu and Windows to.
You can then reboot into Windows.