How to delete everything on a camera at once?

I have a Nikon camera and it has 14.0 gigabytes. There's a lot of pictures on it and I always spend time trying to delete all of them for more memory to record longer.

"A Nikon with 14.0 gigabytes" is meaningless
If you mean "A Nikon with 14.0 megapixels"… That too tells us little

Sure that Nikon has some model number

Anyways, there should be a *format* option in your camera
as with any other camera

Format the card & you are ready to go
btw you are suppose to periodically format the card after transferring card contents to your computer

Get the SD card and on the side it should have a yellow sliding thing on the left of it, push it in the other direction and it should delete all the pictures.

P.S. Most of them are yellow but it can be red or wherever you live it can be different colors.