Never mind. It used to hold the brake lines that went from the rear brake to the ABS unit, which I removed.
I just bolted the tank back on and inspected it all and fired it up. No errors, so I took it for a nice slow ride down my street. As expected, no ABS in the rear, ABS in the front is fine (checked in my gravel driveway) and traction control works fine. Now to bolt on the fairings etc and take a longer ride.
Note: my mod was done by removing the rear lines from the ABS unit as RandyN did, but I tried to be more 'stock' and instead of connecting the rear master cylinder to the caliper with a Galfer line, I pitched both lines and plugged the ABS unit and swapped in a line from a 2010 non-ABS rear brake. Sounded great but the line doesn't run as well as I expected. It seems functional but is not as clean as I had hoped. I may do it differently over the winter but for now, so far, so good.