The app always creates temporary local copies of the backups even when its set to only store them on cloud accounts. This is to ensure that there is a backup available if the upload to the cloud account fails. It also makes it easier for the app to retry uploads to the cloud accounts as well as upload the same backup to multiple cloud accounts if configured to do so.
It also maintains a local copy of the last backup, so that a restore can use the local copy instead of downloading it again. Once the backup has been successfully uploaded to the cloud accounts, it deletes previously stored local copies, except the last backup. It can be set to delete this last backup copy as well from the settings at Menu > Settings > Backup settings, as shown below:
Save local copy – when enabled, a copy is kept on the local storage of the phone for all backups created.
Local backup folder – The local folder where the local copy of the backup should be stored. This defaults to the app’s private folder so that the backups cannot be accessed by any other app. It can be configured to stored these backups on any folder on the phone or to other supported storage like external SD Cards.
Keep local copy of latest backup – This specifies if the app should always keep a copy of the latest backup, even if the “Save local copy” above is turned off. Turning this off will make the app delete any local copies as soon as the cloud backups have been successfully uploaded.
Archive Mode backups
Archive mode works by adding newer messages or call logs to an exist backup and thus always needs a local copy of the backup so that it can be appended. For this reason, the above settings to not keep a local copy do not work if the app is set to use Archive mode.