Well, there are a lot of threads and sites out there that profess to help you with this. None of them do.
You cannot actually erase photo albums in your Iphone. Another design flaw. Gasp! There are design flaws with Apple products!
Now that you've gotten over that, here is what you can do.
1) Determine the names of the albums you want to delete photos from. Note that you will not actually be able to delete the albums themselves. You will, however, be able to delete some or all of the photos in the albums.
2) If you want to delete all the photos in the album, make a new folder with the same name on your computer.
3) Now sync your Iphone with your computer via Itunes.
4) In the Photos tab, select the name of the folder in the phone you want to delete photos from.
5) Then "apply"
6) When you are prompted as to whether you want to change the contents of the phone folder with the computer folder, "Yes."
That's it.
If you want to delete only some of the photos, do the same thing, that is, in the corresponding computer folder, load/keep the photos you want to keep on your phone, delete/move out of the folder those you don't.
You are essentially replacing the folder on your phone with the same-named folder on your computer, in which you have already removed some/all of the photos you no longer want.
