I plan to cut ties with my autistic friend.
Why would you want to cut them off?
She is like an unwanted growth in my life.
You should not tell her that though. You should not just cut her off abruptly. Talk to her about it instead.
I have to deal with her bullshit every day. I've said all there is to say and she's annoying me.
If you want to end the friendship that's fine, but if you don't explain why then your friend is likely to be confused. Particularly given that your friend has autism, you owe her the decency of explaining why you're ending the friendship.