Be sure to disable Design Home’s access to your storage to stop the application from saving photos to your library.

You can change the permissions that applications can access in the Settings app on your device. Keep in mind turning off permissions may cause apps on your device to lose functionality.
  1. On your Home screen or App Menu, go to the Settings app on your device.
  2. Tap Apps.
  3. Find and tap on Design Home.
  4. Tap Permissions.
  5. Tap Storage and choose “Deny”.
Please note that these steps may vary depending on your Android OS, device and manufacturer.