@mrwilsn nice clear pictures thanks for sharing! Can you say, what tools are needed and what locations need to be taken apart to remove the helmet lock?
The seat and the tank need to be removed to get at the tank bag lock on the 2016 and older bikes. Tank bag lock doesn't exist for 2017 bikes due to the introduction of the lockable storage tank.
The seat has 2x 5mm allen head bolts (I think some bikes/years use Torx for the seat bolts but my 2014 Zero S and 2017 Zero SR use allen head).
After removing the seat you have access to 2x 3mm allen head bolts on either side of the tank next to where it meets the seat.
Then there are additional 2x 3mm allen head in the tank bag area.
Next are 6x Phillips head (PH2) on the tank 'bat wings' (one screw on each side is hidding in the hole at the bottom of the black plastic on the front of the tank).
At this point you can remove the tank. Optionally you can remove additional 2x 3mm allen head to remove the black plastic at the front of the tank above the horn.
You may need to snip some zip ties to move some wire bundles around to get access to the 2x 4mm allen head bolts holding the tank bag lock in place from the bottom.