How to delete photos from my iPhone that are in an album?

I have about 6, 000 photos on my iPhone 4S. So I'm obviously running out of storage space and I need to delete a lot of them. Here's my problem: a lot of my pictures are duplicates of each other but in different quality. I want to be able to put those similar photos I have taken at different times and put them in an album, I want not only to remove the ones I don't like from that album, but ALSO FROM MY IPHONE COMPLETELY. I know that that doesn't work so I'm in desperate need of help to figure it out… Maybe an app!

Press and hold one album then check all the albums you want to delete and press the red delete icon

I'm amazed you can type an entire paragraph but you can't delete a picture