The specs ( http://java.sun.com/javame/reference/apis/jsr118/javax/microedition/lcdui/Displayable.html#removeCommand\(javax.microedition.lcdui.Command) )
tell it is allowed to remove a command not attached to a Displayable.
However, MicroEmulator gives an NullPointerException when trying to do so.
Issue item has been moved to http://code.google.com/p/microemu/issues/detail?id=9