Hi Steve,
I believe this could theortically be possible, however I would have to do some further testing to confirm this. It would also likely require some heavy modification to that screen. May I ask, why do you want to remove the date completely? I undestand that when a job is being done in-house, you probably have a queue that you do the jobs as you said, first come first serve. Is having the date field causing issues with your process? Would it be possible to assign a future date and just change it when you are actually start working on the job in-house? Again, I can look into this I just want to make sure that it is worth your while to remove the date from these in-house workorders altogether.
-Ben