Humminbird HELIX 9 Operation Manual page 36

Turn off Sonar
If you're using your control head for GPS/Navigation functions only, use these instructions to hide all sonar views from the view
rotation. When it is set to Off, this is setting also stops the unit from pinging, so all sonar operation is deactivated.
1. Press the POWER key.
2. Select Sonar.
3. Select Off.
NOTE: You can also turn on/off Sonar from the Main Menu > Setup tab > Sonar.
Set up Sonar 36