Carousel is Dropbox's dedicated photo and video managing app, and it recently rolled out an update that lets you automatically remove old content that's cluttering up your phone once it's been backed up to the cloud. Switch on the feature -- as we'll show you here -- and you can avoid running out of room on your phone or tablet.
The first step is of course to get the most recent version of the app installed on your iOS or Android device. If you already have Dropbox set up you can tap to sign in, otherwise you'll need to provide your credentials to gain access. The free up space feature can be found in the Settings menu link inside both the iOS and Android versions of the app. After a few moments' calculation, you'll be told how much space you can clear.
Tap the Free up (X)MB of space button if you're happy for the local copies of these pictures to be deleted; remember they're safe and sound in the cloud and on the other machines you've connected to Dropbox (three copies of every file is a good baseline for backups). The erased files can still be viewed from inside Carousel, but your device's internal storage now has more free space to save the next batch.