How to delete all photos from iPhone 4?

I have searched the internet for days and I can't find an answer to this. I have synced all my photos to my computer on iPhoto and now all I want to do is delete all the pictures off my phone! I researched it a little bit and I kept finding people say you had to update your phone to 6.1, so I did that only to find that when the update finished it had synced every picture from iPhoto onto my phone! Now my phone is completely full and I can't sync music onto it anymore (Which is what started this whole thing. I just want to have space on my phone to have more songs!). Before I tried this I only had about 300 pictures on it and now I have about 1880 so obviously this made it a WHOLE lot worse. I have tried going to "Settings>General>Usage>Delete Photos and Camera" but every time I do this nothing happens. I really don't think this is supposed to be as difficult as I've been making it but I'm starting to get frusterated since this has been going on for several days. Please Help?! Thanks

Also, I don't want to go into a Sprint store since they probably are going to need my computer since it has music, pictures etc on it.

In iTunes, remove the check to sync photos. Plug in the phone and the photos will be gone from the phone.

Do what I do, just use windows explorer. Open Itunes, connect phone, open windows explorer… Then just highlight and delete all at once. I do the same thing for copying photos to computer.