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Is it possible to uninstall Ubuntu 12.04/13.04 and if so how?
I am currently dual booting it with Windows 7 (and it wasn't installed via Wubi and I don't have a system repair disk.
You can unninstall by formatting the partition where Ubuntu is. You can do this by either downloading a partition manager software for Windows(like Magic Partition Manager) or by using gparted live-cd. You maybe wil have to use Windows installatio disk to repair the boot of Windows or you can use a Ubuntu live cd and install grub again on the disk. Recommended the use of Windows installation disk.