...actually, have you done Jack's mission yet?
Unfortunately at this point I've done everything except a half-dozen N7 missions, and Legion/the relay.
Then I'm pretty sure you're stuck with her. While it is possible to kill off some loyal sqaudmates, I don't think it's possible to kill off enough for Miranda to be killed holding the line.
On the up side, at least you can do away with Mordin if you like.