[Updated Nov 11, 2019]: The new Group Privacy setting is now available to all WhatsApp users worldwide. You can update your WhatsApp to the the latest from Google Play Store or download the update here.
It was earlier reported that Group Privacy setting that makes you choose who can invite you to a group or not was in works, now it is rolling out to all beta testers.
The new Group Privacy settings option allows you to blacklist certain contacts from inviting you to groups while still allowing group invites from trusted sources.
The Group Privacy Blacklist function replaces a previous option which prevented all users from automatically inviting you to groups with a new setting named “My contacts except…”.
In cases where group invites are blocked, users will be prompted to send you a private invitation through the individual chat, giving you the chance to join the group.
Go to settings>> Account>>Privacy>>Groups and choose or prevent users from automatically adding you to groups without your permission.
The feature is now available for both Android and iOS WhatsApp users worldwide. Update your WhatsApp messenger and the feature will be live.