I believe you should be allowed to leave a clan after roster is locked if you are not part of that war. This allows for anyone who is asleep or maybe entered that clan to help with an EB and is then asleep to leave if they wake up to find a war is about to take place. Yes, I know they should know when war is; but circumstances arise, such as above. I'm sure you have the ability to lock the roster for only those warring; and maybe lock it for all one hour before war, thus allowing a little flexibility.