iterator.remove();

This code removes the current element from the collection being iterated over by the iterator. It is a method provided by the Iterator interface in Java.

Here's an example of how it can be used:

List<Integer> numbers = new ArrayList<>();
numbers.add(1);
numbers.add(2);
numbers.add(3);

Iterator<Integer> iterator = numbers.iterator();

while (iterator.hasNext()) {
    int number = iterator.next();
    if (number % 2 == 0) {
        iterator.remove(); // removes even numbers from the list
    }
}

System.out.println(numbers); // [1, 3]

In this example, we create a list of numbers and then create an iterator to iterate over its elements. We use the `remove()` method to remove even numbers from the list while iterating over it. Finally, we print the list to confirm that even numbers have been removed.