1. To prevent access to a particular area or thing. In this usage, a noun or pronoun can be used between "close" and "off." We had to close off that section of the restaurant for a private party. I had to take a detour on my way home because the water department closed a bunch of streets off.

2. To avoid emotional connection with others; to isolate. In this usage, a reflexive pronoun can be used between "close" and "off." Todd really closed himself off after his last break-up. I have a hard time making friends because I usually close myself off from other people.

3. To refuse to listen to viewpoints, ideas, or opinions that differ from one's own. In this usage, a reflexive pronoun can be used between "close" and "off." Grandpa, you can't just close yourself off to the ways of the modern world. Can you please listen to what I think, instead of automatically closing yourself off?