I have found the portion of the button where you click to collapse the two sets of icons that run down the left side of the screen that display your recruited NPCs and your cities small and difficult to click on.  I can do it, but it seems the active part of the button that responds to clicking is very very small.  Another button that acts similarly is the little arrow above a unit's picture to eject them from a city.  It seems to have to be clicked right on center or the unit doesn't eject.  I've got the hang of that one, but sometimes I still slip up.  It would be eaiser for me if that active portions of those buttons were a little larger.