How to back up an iphone 5S photostream then delete it off my phone?

I have an Iphone 5s, and am going on a trip and need to get all my photos off my phone so I have more room. I have a windows computer, and am trying to get my photostream photos from my phone onto my computer and got some yesterday but not all because I had to leave. Now I can't get hte rest on. I was doing it via Icloud because that is all I can do for photostream. Please Help ME GET THE REST ONTO MY computer! I also do not know how to delete all the photos off my photostream! HOW DO I DO THAT?

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Get an Android phone.

Turn on or create an iCloud account