I believe that's calling for removing the vacuum hose from the switching valve in the ACV. It might be the light blue vacuum line on the ACV in the diagram, but I can't be sure.
The switching actuator is designed so that when vacuum is applied to it, airpump air will flow to the exhaust ports (port air) rather than directly to the cat. Normally at idle the engine vacuum will open switching valve and the air will go to the exhaust ports, before the O2 sensor. That's why if you hook a wideband to a 7 with emissions it will read super lean at idle. When you disconnect that hose from the switching valve it will remain closed and airpump air will instead flow to the cat (you will probably have to plug that hose you disconnect).
That's for the FD, which is a bit more sophisticated, but you get the idea.
From the factory, the ECU will decide when it's time for air to flow to the cat. At this time it will engage the switching solenoid and the solenoid will cut vacuum to the switching actuator, which is the equivalent of disconnecting the hose. So technically you could put the ground wire on the switching solenoid directly to ground all the time and it would accomplish the same thing.