It can be deleted on your side. It can't be deleted on recipient's side. (Basically just like regular text messaging or even email work.)
Which...in a way it should be, better think twice before sending a message.
But then again, I've send messages to the wrong person./ashamed
Interesting statement about something that so many people use on a daily basis.
Mostly in the States, most of the rest of the world uses Whatsapp and/or different messaging Apps.