Of course you can then delete the partition. The fastest way is to start with the win recovery/install cd go into the recovery console and type fixmbr. (This will annihilate the grub boot manager from the MBR (master boot record) and reinstate the Microsoft one. (which will ignore any os besides windows)
After that you go into the partition manager in windows. The fastest way is to type: WIN-R,
write 'diskmgmt.msc' in the window that pops up.
There it should see the ubuntu partition as "unknown partition type" simply reformat it. If you're not sure what you're doing there, ask again. Making a mistake there can do a lot of damage.
Of course you could also just make win start after a few seconds instead of Ubuntu.
Type F2 in ubuntu, or go into the gnome-terminal. Type
Code:
sudo gedit /boot/grub/menu.lst
You can read through it, it will shed some light, but you can ignore the whole ## (explanations) part, and scroll down to where it sais:
Code:
title... [b]Ubuntu[b]...
root...
kernel...
initrd...
quiet...
savedefault...
And just cut and paste the paragraph that sais
Code:
title... windows...
...
...
...
Above the "ubuntu" one.
This will make win start first. Don't be confused if there are multiple ubuntu entries, those are the entries for the older kernels, just ignore them. Somewhere on top of the file you can reduce the interval, so win starts after eg 3 instead of 10 seconds. (it's self explanatory, you'll find it)
This way you can still boot into ubuntu whenever you feel like it.