How to delete photos off Iphone 4?

I have 2 more folders that are not the camera roll, and I can't seem to figure out how to remove them from the phone. I have tried going in from my computer but they don't come up as being on the phone. Also I have went in via Itunes and clicked sync then unsync then delete all photos but they are still there on the phone. Besides those two ways does anyone know a way in which they can be removed? Thank you.

Added (1). To the first person that responded that option is not available when I click edit it will only let me move the photos to a new folder or share them. I can't delete the folders or the photos. Any other ideas?

1. Go to the 'Photos' app.

2. Tap "Edit" in the top right corner.

3. Tap the little red minus icon.

4. Tap "Delete".

5. Tap "Delete Album".

6. Repeat steps 3-6 if there are more unwanted/unneeded folders. When you are done, proceed to step 7.

7. Tap "Done" in the top right hand corner.

The unwanted folder(s) will be deleted forever when steps 1-7 are complete. I hope this helped!

**As far as I'm concerned, this works on iOS 6.0 and up**

EDIT: Sorry, no. Go to an Apple store or if you don't have time, call Apple support because I really thought that would work.

1) Open photos on your device.
2) bottom of picture is an icon of a trash can or delete button.
3) Click that like you are clicking the radio channel button in a car.