How to uninstall Ubuntu

You need to first fix your boot manager

1. boot your system using windows installation cd
2. go to "repair your system"
3. use command prompt
4. type bootrec /fixboot then hit enter
5. type bootrec /fixmbr then hit enter
6. exit

This time your system will boot directly into windows after doing this you can delete the partition as mentioned above.

This is the safe way to uninstall Ubuntu.