How do I delete pictures from a coolpix S4000

To delete individual pictures: while viewing the picture, tap the trash can icon on the screen, then tap yes when it asks for confirmation.

To delete all pictures on a memory card: format the card. TAP MENU, tap the wrench icon, select "Format card."

To delete all pictures in internal memory: format internal memory. Tap MENU, tap the wrench icon, select "Format memory."

The delete instructions are in the "Deleting Pictures" section of the manual (page 33 in my copy). The format instructions are in the "Format Memory/Format Card" section of the manual (page 150). If you need a manual, you can download one from the manufacturer's web site at
http://support.nikonusa.com/app/answers/detail/a_id/16763