Re: They want her out of the school!!
The first thing you should do is contact your local Autism Society or support group. I'm sure you can find it on line by putting "autism" and your state in a search engine. If they don't have professional advocates on staff, they'll be able to lead you to them. You might also want to contact the Association for Retarded Citizens (ARC) as they have extensive legal support.
Then, I'd suggest you contact your state's department of education, and ask for their special education office. My guess is that your child's school is not conforming to the Individual with Disabilities Education Act (IDEA). Many principals are not as familiar with it as they should be (or they just hope that you're not!). Of course, the school is only bound by the IDEA if they have proof of your child's disability.
Bottom line is that your child has a right to an education, and to deny her that right is to discriminate against her on the basis of her disability... and that's a big no-no!