a) Ejecting workers from a production site
E.g. a normal mine starts with a miner, who gets better and sometimes turns into a chief/master miner. For a deep mine you need a chief miner and an normal miner. If another mine happens to be finished while an enhancement from normal to deep mine is underway, the chief/mater miner that got ejected for the enhancement works somewhere else and you may end with a deep mine with no chief miner around. SO: How about adding a button to eject the current worker from its location? The same situation applies to the smiths and other professions, too.
b) Ejecting raw materials from a production site
If your economy is in deep shit creek because you forgot to build a rangers hut and your last pieces of lumber idle around in the production that is currently not active (e.g. at the toolsmiths house), it would be nice to be able to kick those lumbers out and back on the market to be able to build the rangers hut (or another lumberjack somewhere else).