You probably installed Ubuntu on your Windows machine just to check out the open-source operating system everybody loves to talk about and boast about but you have realized that it is not your cup of tea. There are many applications and features that you have gotten used to in Windows that are either not available in Ubuntu, or it is very difficult to install them and then tweak them. There is still lots of command line stuff that you need to do in Ubuntu in order to make it work according to your preferences and this requires you to know lots of Linux commands.
People who are already comfortable with Linux commands may not find it difficult to use Ubuntu, but if you started using your computer way after people were using DOS, Linux and other such operating systems, you will find it tedious and difficult to use long strings of commands just to download programs from various repositories and then install them. Sometimes it even doesn’t seem worth it.
Another problem many people have faced is that even when they have finally gotten to using Ubuntu, suddenly there is a program that simply refuses to work. All these nags are forcing many people to either uninstall Ubuntu completely, or just let it be there when Windows becomes the primary operating system again.
Why would you uninstall Ubuntu?
Frankly, there is no big reason to uninstall it if you have got lots of space and it is simply on another partition. It normally does not hog your system resources while it is just there. So there is no need to get rid of it even if you don’t need it. You would only uninstall if you are in dire need of more space. Once you have installed Ubuntu it takes over your bootup sequence and your computer boots in Ubuntu. You can easily change the sequence so that your computer boots up using Windows. You may like to read How to change the boot sequence or grub boot order in Ubuntu — slightly old blog post, but you can use the information from there
Getting to the uninstallation part
There are two ways people install Ubuntu on their machines as dual boot up (having Ubuntu and Windows running on the same machine).
One way is installing Ubuntu from within Windows just like any other program and your computer turns into a dual booting machine. It means your computer can be booted from Windows as well as Ubuntu and it depends on your preference. The program needed to install Ubuntu from within Windows is called Wubi. If you use this, then uninstalling Ubuntu is simply a breeze. You can use the Wubi uninstaller.
The real problem comes when you installed Ubuntu from outside of Windows – booting your computer from an Ubuntu DVD and then creating a separate partition for installing the operating system. Then it becomes quite a tricky task to achieve. This article on Make Use of has done a better job of explaining how to uninstall Ubuntu from a Windows-running dual booting machine.