As of version 10.1.35, you can set all buttons, not just the Back button, to be invisible but still clickable in the kiosk.
2. Go to Customizations-> Buttons (You may have to click the right arrow on the top bar to scroll to the Customizations tab)
3. Search the Button you want to Hide
4. Click the Back Color option for that button
5. Check ‘Opacity’ and put it to 0.00
6. Click Set
7. Click the Custom option for that button
8. Put in an empty space to overwrite the text for that button with nothing.
Now both the button and the text on it will be invisible, but the button itself will still be there and clickable.
The Back button on the Visitor Sign-in Screen actually has it’s own option to made invisible but still clickable.
2. Under Visitor Management-> Advanced Options, check but ‘Hide Back Button on Sign In’ and ‘Make Hidden Button Clickable’