What levi said about passing it into the constructor is correct, but you could also use an object.
I think what Veverke is trying to say is that you could easily use the delete keyword on an object to achieve the same effect.
I think you're confused by the terminology; properties are components of the object that you can use as named indices (if you want to think of it that way).
Try something like this:
var obj = {
"bob": "dole",
"mr.": "peabody",
"darkwing": "duck"
};
Then, you could just do this:
delete obj["bob"];
The structure of the object would then be this:
{
"mr.": "peabody",
"darkwing": "duck"
}
Which has the same effect.