[jQuery] How to prevent a particular field being submitted in form submission

I have email, password and some other fields, and I'm using $.post to
send data for Ajax submission.

$("#MyForm").submit(function(){
$.post('/register.php',
$(this).serializeArray(),
callback,
"json"
);
return false;
});

The problem is that I don't want to submit a particular field.
The serializeArray() returns all the fields in the form. So, I tried
something like this to prevent the password field being serialized.

var serialized = [];
$(this).serializeArray().filter(function (value, index) {
if (value.name != "data[User][passwd]") {
serialized.push(value);
}
});

This works great but the ajax submission doen't work.
Is there any solution for this?

Many thanks!