My HWH system will allow the coach to settle all the way down when I push the on button twice, allow it to lower the coach until the hydraulic pump starts. then shut the system off, then restart the system again by pushing the on button twice again, this will start the cycle again and allow more air out until the coach is as low as it can be.
If you want the coach level as low as it can be. simply turn the system off again, then push the on button once and run the jack position that is lowest. (in the manual mode)
Forgot to add, HWH systems allow air to escape on a timed cycle, not a pressure reduction cycle.