Today, WhatsApp has introduced an option to allow only admins to send messages in a group. The option is available under the Group Settings menu.
This feature is for those groups that has been created just for announcements and information. So, other people can not send any random messages in group to start irrelevant conversation.
To enable this setting, open ‘Group Info”, tap “Group Settings” and select “Send Messages”. Here, select “Only Admins” if you want just admins to send message.
If, as an admin, you change the setting, other members will be notified. Admin can change the setting any time and allow other members to participate in conversation.
Now the setting is available to all users across the globe. The feature is available for both Android and iPhone apps. You should update the app to see if the option available.