This is a tough one to answer. I had a veep that was the same way. We just toughed it out that year. Knowing then what I know now? I'd have:
A) Posted a notice of intent for 30 days prior to the next possible meeting and taken it to a vote. I'd state our case and let her state hers and then let the votes fall where they may.
Changed the bank accounts and locks and just told her up front that she was fired.
... but that's me...
I will tell you that those suggestions would follow talking to her first. Get the rest of the officers and face her down. Get the principal involved. Document everything. Have an intervention. Get a mediator. Then, if you can't resolve your issues, take it to your members for a vote.
This year we rewrote all the bylaws (a long story in itself...lol) and one of the things we included was how to fire an officer and what an officer could be fired for. Remember, you can not do much if she just doesn't agree with you. She really has to be breaking rules, ignoring rules, etc. Not being a 'yes-man' doesn't fall into either of those catagories...
Good Luck!