Enabling Jooki’s “airplane mode” will prevent Jooki from connecting to Wi-Fi.   
In airplane mode Jooki cannot stream from Spotify. Once enabled, airplane mode will remain until switched off.

Enabling airplane mode: push the Prev/Next knob to the left and hold it for 10 seconds. A sound will notify you that the airplane mode is on. 

Deactivating airplane mode: push the Prev/Next knob to the right and hold it for 10 seconds. A sound will notify you that the Wi-Fi connection is back on.