How to hide / dismiss your application and send it to the background?

So I would have thought this was pretty common but basically I am trying to add a “Remind me in 15 minutes” button to my application. I have all my logic working, I just basically need to app to “close” / go in the background / minimize / whatever the technical term is. Essentially right now if I hit the button and hit home, on iOS or Android everything works exactly how I want. I just want the app to go away as soon as you hit the button and I have everything else setup, Any idea?