Wheres the off button??

Only getting two stars from me because once I opened the app to explore it, I was checking out brainwaves.
Now the only thing the app is showing is "Sounds" option.
This is insane!!! I need my phones sound on but Im about over 2 hours of brainwaves!!!
Doesnt even turn off even if delete the app

iPhone vs droid app about Deep Calm - Nature Sounds, Sleep Music, White Noise Help You Get Better Sleeping App