I noticed that the settings menu of the touchscreen plugin contains a link to the Volumio Shop, which basically opens the Volumio website. It does, however, not show any way to leave this website again, except by hard resetting.
Have a look on:
https://volumio.org/forum/volumio-deezer-browser-access-t6709.html
You can open Volumio in non kiosk mode with chromium browser tabs.