It's clear as mud. Page 154 of the owner's manual:
After turning the “ENGINE START STOP” switch off and opening and closing
the doors, the steering wheel will be locked due to the steering lock function.
Operating the “ENGINE START STOP” switch again automatically cancels
the steering lock."
You'll just have to (A) leave someone in the car while towing. or (B) leave a window down so you can reach in and push the ENGINE START STOP switch again to cancel the steering lock. (C) Check with a Toyota service technician and see if they have a remedy.