Can I sell a call option that I bought earlier on?

I'm still newbie in an investing world. I'd like to know, if let's say I bought a call option contract at the money. After sometime, the contract has become in the money (and it's before the expiry date). Can I sell that contract so that I can earn the remaining time value, aside from the intrinsic value? And if the answer is yes, does that mean I have the obligation towards the person whom I sell the contract to?