I was accepted to college and I accepted the admission, they sent me a packet and everything, but I just realized I can do my associates degree at a community college for free. Can I defer admission to the fall 2016 term place I'm admitted to? Should I defer and go to the free place or would it be best to attend the college I accepted the admission to already?
Different colleges have different policies on deferral of admission. You will need to contact the school to ask them about this or consult this list of schools and deferment policies to see if your college's policy is listed. Note that many schools do not allow you to receive academic credits from another institution during a deferment period, so you might not be able to take the free classes you mention while retaining your spot at the college.
If your school allows a deferment, the question of whether you should take advantage of it or not is also dependent on information not included your post. If you think you'll be in a better place financially and mentally for a four year college if you put it off for a while, and you are allowed to attend community college classes in the interim, then it might be a good idea to wait. However, if going to college next year is financially manageable and you're fairly sure about what you want to study, you should probably go ahead and enroll.