Have you ever heard of the term "gap year"? That may be what your daughter is attempting to do right now- take a year off from school and work for a while, until she has a chance to figure out where she wants to go next. And there is NOTHING WRONG WITH THAT. If Malia Obama, president Obama's older daughter, could do this, then so can YOUR daughter. She took a gap year and is now at Harvard University.
What you need to do, pal, is GROW UP SOME and recognize that just because your daughter is working a minimum wage job NOW, she's unlikely to stay there or at that level for the rest of her life. Her perspective will change as she gets older, and being a waitress will become less appealing. And BTW, there's nothing wrong with working in the hospitality industry. It actually is one of the more lucrative fields around, and it's also relatively recession proof, which is important. There will always be a need for people to work in restaurants, hotels, motels, etc., because America is a mobile society in which people travel frequently.
NO, you shouldn't throw your daughter out. What you should do instead is ask her to start paying you a percentage of her salary as rent. She also needs to start buying most if not all of her own food and personal necessities, like clothes. She should be responsible for her own medical care and transportation costs, too. Making her do these things will teach her life lessons that she needs to learn anyway, such as how to make and stick to a budget, how to balance a checkbook, and the proper use of credit. The two of you need to agree on a set of house rules as well. Rules about hours, quiet time, visitation by guests (of the opposite gender as well as by her girlfriends) should be topics for discussion.
I think that once your daughter has been made fully responsible for all of her own expenses, she'll start to realize that she needs more income to gain the lifestyle that she wants. And that in turn will motivate her to seek other employment, or possibly to attend college in order to get a better job that pays more.