Can i save my iphone photos on dropbox?

Can i save my photos from camera roll on cloud apps like dropbox or Box then delete my camera roll? Are these sites safe to leave my pics

Yes you can. That's what I do. You can set it up so that it does it automatically whenever your iphone connects to the internet. Then you can delete them from your phone and they're saved on the cloud. Here's an article that explains how: http://www.maclife.com/article/howtos/how_automatically_sync_photos_your_iphone_dropbox.
Also, here's something interesting I learned: dropbox is an actual physical file on your computer. Even though it's "on the cloud", it exists on your computer and takes up disc space just like any other. The advantage is that it's available on all your devices, accessible from any computer and synchs automatically. But don't have any misconceptions (as I did) it still takes up disc space on your hard drive. This is good if dropbox were to ever crash but it's not so good if you're using it hoping to free up space on your hard drive.

Yes you can but it would be better if you do it with iCloud