Yes you can. You will have to go to a community college. They will give you a entrance test. This is basically to see where you are. If you pass you are in. If you fail you are still in they will just require you to take prep courses before you take the regular courses. I failed the English part of the test. I had to take an english prep course before I could take regular english classes. My regular grade schools were not very good at teaching english. The prep course helped a lot. I even met a life long friend in the class. All the rest of my scores were good. I got to take regular course in everything else except for that dang english. If you want to go to college, GO! Maybe you left school early because you did not see the need or maybe you had to leave for a reason. It looks like now you are older and see the need for an education. Good for you!!! People with a college degree earn a lot more money than those with out one. Also I noticed that people who had been out of school working and living on their own did far better in college than those who came streight out of high school.
You don't need a highschool diploma in order to get accepted in a community college. But you have to take some clases, generally maths and science.
Not at most universities and/or colleges due to the fact that a high school diploma is normally a pre-requisite to entrance.
I know someone who attended and graduated from Georgia Tech without having his high school diploma. He went through the 11th grade, took an entrance exam at Georgia Tech and they accepted him for the following year! Don't count on this, it would be very rare I'm sure.
You need at least a high school diploma, unless you go to itt tech or something.