its not too late to withdraw and you probably get all deposits back. See https://students.ucsd.edu/academics/enroll/withdrawal/withdrawal-undergraduates.html
As to whether its a good idea to go to a CC instead, that discussion could fill pages and pages. Here are a few things to consider, others may add more in addition to what is written above. Many of your peers at a CC are going to drop out before they get a 4-year degree, so to the extent they influence the level of class discussion, instruction, and what is the “norm” for studying and doing homework that can be a drawback. Its easier to make friends at a 4-year when you start as a lost frosh like everyone else; by junior year many kids have made their core group of friends and aren’t looking for more. If you are outgoing this may be not much of a factor. In terms of getting to know profs for recs you have 1 year if you start as a junior since you’ll be applying for grad school or jobs in the front part of senior year. And unless you were planning on living at home at UCSD, many people would say a lot of what they gained in college came outside of class as they met people with other backgrounds and point of views.
that said, many people xfer and are happy with their experience. Talk it over with some people who have done it both ways (4-year at 1 school or xfer) perhaps older siblings of some of your friends. There is no universal right/wrong answer here, you pays your money and takes your chances…