You can easily opt any user out of data collection through the Localytics SDKs.
Specifically, you can call
[Localytics setOptedOut:YES] or
Localytics.setOptedOut(true) to opt a user out of data collection, and check their status with
[Localytics isOptedOut] or
Localytics.isOptedOut(). This will upload an event to Localytics saying that the user has opted out of data collection and will prevent any further events or sessions being uploaded.