Fairly simple concept. There are cases when you may wish to convert trained troops into regular settlers again or into other troop types. Could we have a second tab on the Barracks page where you can 'release' any troop type back into it's settler equivalent and to 'retrain' troops within the same type - for example train 1 Bowmen with X Long Bow's to become 1 Long Bowman. I found that I ended up the other day with a bucket load of normal bowmen that I was never going to use as I now had Long Bows. Equally there may be cases where you've trained up a specific troop type for a particular camp but might not wish to keep them.