You can appoint a new deputy if you stand on the high rock, go to the fireclan territory on the beach and kill the leader after if you go to the dens and speak to the peachy coloured cat (forgot her name) she will tell you to calm her daughter down in the warriors den, go inside the den and speak to her daughter, you can meet up with her at fire clan border and she becomes the leader, after you just wait until you die of old age