It depends on what kind of meeting you are talking about. With a friend: "Bye, see you later..." A business meeting: "Thank you" and something relating back to what you discussed.

If you are in a formal meeting at work then the chairperson will close the meeting by saying, "If there is no further business to discuss, I now declare this meeting closed." He will then say the time and the secretary will write this down. If you are with business associates, you can say,"It was nice meeting you Bob or Mr Smith. I look forward to our next meeting in September etc"

Business? Well, I think we can wrap it up for now/today, thank you, nice ....blah blah blah Casual? then it doesn't matter, does it, say "i gotta go, nice meeting u " or "do u like to go?" something like that. But it really depends on the content and place of the meeting and the people involved.