Do you miss something on BrainKing.com and would you like to see it here? Post your request into this board! If there is a more specific board for the request, (i.e. game rule changes etc) then it should be posted and discussed on that specific board.
baudrillard: What you could do is just rename your account to something like "gone123". Then send Fencer a note asking him to change your password. Then *poof* - you will no longer be able to log in.
One of the features of BK is that it keeps all the game history and such - so to remove an account completly may mess up the database and such. So in my opinion, a quick rename and a quick note to Fencer asking him to change your password so you can never log in again would probable work best.