I think removing recordings from the Recordings windows would defeat the purpose of the function, which is to show all recordings that have been made.
I also think that it would break the "Do not record programs that have been recorded in the past" functionality, as I believe that functionality uses that list.
If what you are trying to do is identify which recordings you have already moved, maybe there is a better way to do that, rather removing them from that list. Perhaps in the Tooltip showed program information, as other views do when you hover over a recording, including the file path and name, that would be better? Or if the path and/or filename could be optionally added to the view. But then we are getting closer to a normal, custom View.
Custom Smartlist
How about a new Library field called [New], which you set for all recording rules. Hmmm, that is likely to be forgotten, and wouldn't be automatically set. Okay, a new field called logical Integer field with a Check Edit Type, call it [Moved], which starts out empty.
Then a new Smartlist that displays all recordings that don't have the tag [Moved] set. It would probably be good if this Smartlist could be restricted to the "Recordings" database, in the same way that a view can be restricted to the "Television Guide" database. That capability doesn't exist at the moment for Recordings, so it would have to be added as a database that a View or Smartlist could be restricted to. Yaobing, is that possible?
Then sort your Smartlist by recording date, and as you move each recording, tick the [Moved] box and it will vanish from the list.
Acceptable workflow?