how do i delete picture from my iphone

Your question is a little bit vague. How did the photos get on the phone? If you took the photos with the phone or if they are screenshots, you can delete those photos right on the phone via the trash can icon.

IF the photos were synced from iTunes, you must connect the phone to your computer, and unsync the photos using iTunes again.

Sync photos from your computer to your iOS device using iTunes - Apple Support