Removing items from a nested ICollection

Hi,

Given the following classes

public class A
{
    string Id { get; set;}
    ICollection<B> MyColB { get; set; }
}

public class B
{
    string Id { get; set }
}
List<A> MyColA;

Assuming that MyColA has been populated with several items. How do I find and remove a B item with a specific Id from all A elements in MyColA.

Regards

Alan