How to wipe all pictures from iphone5?

I synced my iPhone and now I have loads of unwanted pictures that its not letting me delete.

With your phone plugged into the computer, go to iTunes. Click on the left sidebar option that says "[Your] iPhone" and then go over to the "Photo" option. From there, select to only have certain albums on the phone. You may have to sort the photos that you don't want into a separate album--or delete them from the folder entirely if you don't want to keep them on your computer, either.