As someone who has gotten rid of 3 incompetent bosses...

I have to agree that you have to let your boss know what you intend, and give her a last chance. And then face the possibility f a serious baklash. Yes, I managed to get rid of 3 bosses, but in each case 1) I was prepared to leave the company, and 2) the boss was also not performing from a results point of view.