I want to tease one of my co-workers until she quits.
That's very mean. Why do you want to tease your coworker like that?
Because I don't care about her; she's just an obstacle to me.
You're expected to act professionally at work and so it is very unacceptable and inappropriate to continually tease one of your coworkers. It's especially wrong if you do so out of malice and a desire for that coworker to quit her job. If you have issues with your coworker, you should try to discuss them with her and work out a compromise rather than try to get her to quit her job since that will have a large negative effect on her finances and well-being.
I'm late for work, mum's going to kill me.
It sounds like you're not worried about being professional like you should be; instead of trying to bully a co-worker into quitting I'd worry about keeping your own job if I were you.