Turn off 2nd extruder on FlexyDually v2

I have a Taz5 with flexy dually v2 and just updated to Cura v3.2. I can’t figure out how to print on the T0 extruder and leave the T1 extruder off. Every time I try to print a single material print it heats up the T1 extruder as well despite no material being assigned to this extruder.

How do I turn the T1 extruder off?