Uninstall Ubuntu using Windows

Suppose you are running Windows. If so, follow these steps:
1) In Windows, launch Disk manager and remove every partition used by Ubuntu (root partition, swap, …)
2) Reboot with your Windows CD. When asked, choose “repair” and launch fixmbr. This command replaces GRUB with Windows bootloader.
3) Reboot again and you have done.
Once you are done, it you want to recover the space for Windows that was once used by Ubuntu. You can use the steps outlined above (going the the Disk Manager, etc). To create a new NTFS partition and assign it as something like the D: drive (or some other letter) to be used for data and so forth.