I am a man and want to get married due to fear of sin. My parents won't allow it because I am in college. Should I marry now without telling them and then tell them later about the girl without saying I was already married to her?
Bismihi ta'ala
Unfortunately, many young adults face this same serious problem of certain parents with a wrong mindset preventing their son/daughter to get married, under the assumption that marriage will hinder their studies, or career prospects.
We must invite people to adhere to our Islamic recommendations, and keep ourself immune from sin or engaging in illicit or secret relationships.
I would not advice you in any way to secretly get married, behind your parents. This is something that would not be to your benefit. Try to prove to your parents that you are ready for marriage. Show that you are mature, and you have the ability to combine between your college and having a partner. Even if it means your engagement period can be a bit long, but as long as you do not do something haram, or without your family's blessings.
With prayers for your success.