cordova-plugin-allow-backup

Any Android applications that target Android 6.0 (API level 23) or higher automatically participate in Auto Backup. This is because of the android:allowBackup attribute, which enables/disables backup. The property defaults to true in cordova-android projects as it is omitted from the AndroidManifest.xml file.

<application ...
    android:allowBackup="true">
</app>

This may cause you an issues if you are trying to clear localStorage as it will automatically be restored when the app is re-installed. As well the phonegap-plugin-contentsync project stores it's files in a backed up directory on Android.

If you don't want this default behaviour on Android you can disable Auto Backup. Include cordova-plugin-allow-backup in your project:

cordova plugin add cordova-plugin-allow-backup

If you want to set the property to true use the BACKUP  variable.

cordova plugin add cordova-plugin-allow-backup --variable BACKUP=true

UPDATE!!!

So I totally biffed on the fact that edit-config is now supported in config.xml as well as plugin.xml so you don't need the above plugin. All you need to do is add an edit-config section to your config.xml file like this:

<platform name="android">
    <edit-config file="AndroidManifest.xml" 
                 target="/manifest/application" 
                 mode="merge">
        <application android:allowBackup="false"/>
    </edit-config>
</platform>