For a change, I will be talking about how to uninstall Linux Ubuntu (or other operating systems) from a dual boot windows pc, and still being able to boot into other OS without much work. So let’s get started right away.
Backup your Linux files

It pops up everytime, but backup really is very important. If you have been using your Linux system for some time, chances are you would have created files you wouldn’t want to loose. In such a case, you can boot into Linux, backup your files (check out your Home directory) on an external device or onto a Windows partition.

Alternatively if you somehow managed to mess up and can’t boot into Linux, you can use ext2 IFS which allows you access to your Linux paritions. It can only read ext2 and ext3 filesystems though. If you are using other filesystems, you would have to look around a bit for a similar application. In any case, you can always boot from a Linux live CD to backup files if everything else fails.

Delete Linux Partitions

Next step: delete every Linux partition. That would include everything – boot, swap, home, whatever way you set up your system, it is time to delete all Linux partitions. There are a couple of ways to achieve this, easiest being from within Windows’ Computer Management. You need to:

Log in to an account with administrative privileges.
Right click on My Computer, click ‘Manage’.
Choose ‘Disk Management’ listed under ‘Storage’ and you will see all of your partitions listed there.

how to uninstall ubuntu from dual boot windows pc

Next, you need to identify Linux partitions. The Linux partitions generally don’t have a file system listed with them if Windows doesn’t recognize it, so this can serve as a clue. Other ways can be identifying by size or partition number. You can use partition managers, these are generally better at identifying filesystems. Go ahead, delete the partitions, just make sure you delete the correct ones. Linux is gone and so is GRUB, which allowed you to choose operating system to use at boot time. So currently, you cannot boot into any other operating system, without some help. We are going to fix that soon.
Restore MBR

As we noted, GRUB is gone and so is the ability to boot into Windows. You would now need to boot from the Windows CD/DVD to restore the Master Boot Record. You can also use other Live CDs like one of my absolute favorites and highly recommended HBCD just in case you don’t have Windows installation media handy. Here are the steps:

Boot from Windows CD/DVD and choose “Repair” when it shows up.

Choose command prompt on the resulting screen and run the following two commands:
bootrec /fixmbr
bootrec /fixboot

XP users need to run the recovery console from Windows XP CD and then type fixmbr when at the command prompt.
Reclaim free space

Restart now, remove the CD and you should be able to boot into your Windows installation. Once there, you should go ahead and reclaim the unpartitioned free space which was previously occupied by Linux. Doing so is simple and straight forward:

Fire up Disk Management as before.
Right-click on the unparitioned space, choose new partition or new logical drive.
Specify the size and other options according to your needs and you are done.

The free space should now be accessible from My Computer like any other partition. Alternatively, you can create multiple partitions from the free space or resize existing partitions to suit your needs.You can use utilities like GParted, Easues Partition Master or any one of the many partition managers on HBCD to perform such advanced tasks easily.