Don't "demand" that they be stripped from the roster, but clearly let her know if that there was someone on your half of the list that filled her with dread, you would take her side and that's that.
Remind her that she has an amazing sense of style, and that someone has to be the one to set the next trend! Otherwise, a mistake could buy you a one-way ticket to the couch.
Don't listen to the pinheads who are mortified by change, go with your gut, but, above all else, be respectful to your bride's wishes. If you embarrass her, you fail.
If you have a little "prank" that you think will lighten up the wedding party? Don't. Just forget it. If you must, share the idea with your buddies. But don't actually do it.
Every now and then, we do something useful, something constructive. And that takes us to our Reader Comment of the Day, or what no one calls the "R-COD."
Just have your fiancée find another bridesmaid. Done and done. It's not really that complicated. Surely she has another friend, right? If not, find one.