Actually...it makes perfect sense that you can't remove the extension any time you want just because it's no longer convenient. Otherwise, there would be no point in even having raid reset days.

Think about it for a moment. If you can extend a raid ID indefinitely, then you could extend it a couple of times until, "Oh look at this! We killed Yogg a couple days into the new extension. Well, just reset it, and we can start all over right away. Now we can just keep extending this new id until we kill Yogg again, and then...oops! We killed Yogg and reset it again halfway through another new extension. Rinse and repeat. Anyone taking longer than a week to clear a raid, would essentially never be limited by lockouts in any way.

So, this has to be a tradeoff for it to work. Do we want to extend it and potentially waste some of the lockout by only having a few bosses to down? Or do we want to try again from scratch and get more loot all together.

(Note: In looking at the above paragraphs...I haven't seen so many "extensions" since yo' mama's hair, dogg! OOOOOOOHHHHHH!)

(Second note: I'm sorry...I have no idea where that came from.)