How to delete photos on your iPhone?

I have an iPhone 4 I've had it for a year and a bit but a while ago I plugged it into my laptop to put my pictures on to it but when I did that it added like 200 photos on to my iPhone, there not in my camera roll there in a separate folder called photo library. It won't let me delete the album or the individual photos so I have no clue what to do? I want to get rid of them tho as they take up loads of storage. Any help?

When you look at them individually there should be a little trash can on the bottom right hand corner.

You have plug it back into laptop n delete it that way, you can't delete off phone when it's uploaded off laptop if that makes sense

Go in photos in left side there will be arrow when you touch that then there will be come four option when you touch any photo there will be sign of tick then you can delete that photo

Hook it up with com, click ipod, go to photos, go to sync photos from, click choose folder, there should be a folder called photo library, put it in the trash, delete it or whatever, then you're done.