To stop iHeartRadio notifications from showing up on your Android Wear watch, follow the steps below:

  1. On your phone, open the Android Wear app
  2. Touch the Settings icon
  3. Touch Mute app notifications
  4. Touch the Plus icon
  5. Select iHeartRadio

Additional info: Android Wear - Google Help

Once muted, iHeartRadio notifications will not be sent to your Wear watch, but you will still be able to view the Now Playing and Next cards. You will also be able to start iHeartRadio through the Android Wear Start menu or by voice prompts "OK Google", "Open iHeartRadio".