If you don't want to share photos anymore, then you can unshare them. To unshare photos from Dropbox, tap "Dropbox" app on your Android device. Select the "Albums" view located at the top on the screen. Here you will see the shared albums are listed first and individual photos are listed under "Other shared photos". Select an individual photos or an album which you want to unshare. Tap "Unshare" icon located at the top right corner on the screen. A pop-up window opens up. Tap "Unshare" button to confirm it. Your photos will now be unshared and any existing links to these photos will no longer work.