Delete photos on iPhone

They will remain there, unless you delete them.

If deleted from the Photo Stream, it is deleted from the Photo Stream for all devices and computers.

Photo Steam is iCloud in regards to photos.

That is not always the cause. If i deleted a picture from my ipod photo stream, and it has already been sent to all my other devices, it will remain on all the other devices unless i delete from all my other devices!!!!! GET IT.

Select a photo in your Photo Stream and select Delete for the photo.

The following warning message is provided:

"The photo will be removed from the Photo Stream on all your devices."

GET IT?

Deleting the photo from the Photo Stream on your iPhone removes it from the Photo Stream on other devices, as long as your iPhone and apps on your computer are updated.

See this Apple doc -> iCloud: Photo Stream FAQ

How do I delete photos from my Photo Stream?

You can delete photos from your Photo Stream the same way you delete other photos from your device. Just select the photo you want to remove and tap or click Delete. When you delete a photo from Photo Stream on one device, iCloud will automatically delete it from the Photo Stream album or view on your other devices.

Note: Deleting individual photos from Photo Stream is supported by iOS 5.1 or later, iPhoto 9.2.2 or later, Aperture 3.2.3 or later, and Apple TV Software Update 5.0 or later. You will need to manually delete photos you downloaded to iOS devices running iOS 5.0.1 or earlier after updating to iOS 5.1.

If the photo was captured by your iPhone, the should remain in your iPhone's Photo Library. Photos/videos in your iPhone's Photo Library can and should be imported by your computer as with any other digital camera. Photo Stream is temporary and limited to 30 days and 1,000 photos.