Depending on the context, you might use:
* High school: If you're talking about the level of education, the opposite of college is high school.
* Work: If you're talking about a place where you're learning, the opposite of college could be a workplace.
* Home: If you're talking about a place you live, the opposite of college is home.
* University: While both are institutions of higher learning, some might consider them opposites because of their size and structure.
* Trade school: If you're referring to a specific type of education, a trade school might be seen as the opposite of a liberal arts college.
Ultimately, the best antonym for "college" depends on the specific meaning you want to convey.