Also lose the 10 explorer cap.
The explorer cap is not 25.
I haven't reached 200 dwellers yet, but are you saying you can't build more living quarters (over the 200 limit) and then deleting the living quarters you want to change?
Yes, that is what he means. If you are maxed out at 200 dwellers, then you can no longer build additional living quarters, the option is grayed out. The only way you can destroy a full living quarter at that point is to kill 40 dwellers. That's what I had to do, it wasn't a big deal for me because I leveled up all of them without knowing the huge difference in health points for someone who starts as a level 1 with ten endurance and at least a +5 endurance outfit when they hit level 50, and a level fifty that only had 1 or 2 endurance. So I had planned on replacing them at some point, just kind of a pain to do it all at once.