No, you don't activate/deactivate that setting on the H9. You do that on your ES8 by changing the MIDI CC yout ES8 sends out. For example, you can map MIDI CC 1 to the expression pedal, and MIDI CC 2 to the output volume on H9 (or in H9 Control. See attached image). Then you switch the MIDI CC messages by pressing a footswitch on your ES8.