How to delete a photo album off iphone 4?

I have camera roll, which i want to keep.
and then i have "one album" that i synced off my computer, but then it created "Photo Library" which is just a duplicate of that "one album"
so i want to just have camera roll & "one album" NOT the photo library…
how do i delete it?

It's super easy you go to where you see all you're albums then you will see a edit button in top right corner click it then there will be a red minus simble click it then click delete

You can only delete that one when you connect your iphone 4 to itunes on the computer.