Casting to either a Chromecast or Airplay device allows you to multitask while you have the video playing on the TV (with the exception of Airplay Mirroring). In order to stop the device from casting to your screen, you'll need to go back to the [adult swim] app, tap on the casting icon, and tap on 'Disconnect.' If you have multiple devices connected, you'll need to make sure to disconnect from casting on all devices. You can also disconnect from Chromecast by selecting ‘Stop Casting’ in the Google Home app.