SharedPreferences are not being cleared when I uninstall

Adding to Mo1989 answer , if android:allowBackup="false" clashes with any other library then use tools:replace="android:allowBackup" inside application tag of Androidmanifest.xml to fix the error

This is a new marshmallow feature.

Add android:allowBackup="false" tag inside your <application> object in your app manifest to disable this behaviour.

If android:allowBackup tag clashes with any other library you are using, you should add tools:replace="android:allowBackup" also.