To activate the self destruct messaging function:

*Start secret chat with your friend by swiping from left.
*Choose contact who you want to have a secret chat.
*In the chat select setting on top right corner
*Select Set self-destruct timer

By selecting the function it will automatically delete the message after you have read it.

You can do a group chat by adding your contacts.
You can send a broadcast message to all your contacts without worrying about having them all in 1 group.