Non techie answer - Yes you can uninstall it. I expect at some point you set it so that your pictures automatically upload to dropbox as well. If you don't want to use it as a back-up then remove it however the advantage I find with it (and there are other apps that do this) is it's a really easy way to move photos from one device to another or share with someone else.
I have it on my laptop,phone and tablet and any picture I take on my phone for example, automatically gets uploaded to dropbox on all 3 devices.