How to delete all Photos from my IPhone? Its getting sent in for replacement?

WEll My iphone is getting sent in for replacement due to the wifi not working, So whats the easiest way to do this? I synced and backed it up now I am restoring it now to factory settings , But I just cant figure out how to delete all the photos on here.. I hope it not one by one cuz I have 600 of them :(How to delete all Photos from my IPhone? Its getting sent in for replacement?the best way i think is to sync them out of ur iphone, its more easy and less time consuming.