Delete a data in C#

I've been trying to delete a data in C# but it seems to be null, so here you are, please I need a support of any of you... thanks my friends

/*
 * Created by SharpDevelop.
 * User: fabreu
 * Date: 5/13/2013
 * Time: 1:40 PM
 * 
 * To change this template use Tools | Options | Coding | Edit Standard Headers.
 */
using System;
using System.CodeDom;

namespace ConsoleAgenda
{
    class Program
    {
        
        struct AgendaElectronica{
        
        public string Nombre;
        public string Email;
        public string Numero;
        public DateTime Fecha;
        
        
        }
        public static void Main(string[] args)
        {
            string Opcion;
            int CapacidadContactos = 5;
            int Cantidad = 0;
            AgendaElectronica[] Contactos = new Program.AgendaElectronica[CapacidadContactos];
            string salir;
            do{
            Console.WriteLine("Basic Diary:");
            
            Console.WriteLine("\n1-Add Contact:");
            Console.WriteLine("2-Search contact:");
            Console.WriteLine("3-Search every contact Added:");
            Console.WriteLine("4-Delete Data:");
            Console.WriteLine("0-Log out:");
            Opcion = Console.ReadLine();
            
            switch (Opcion) {
                case "1":
                if (Cantidad < CapacidadContactos) {
                    Console.WriteLine("Contact range: {0}",Cantidad + 1);
                    Console.WriteLine("\nType the contact you wish:");
                    Contactos[Cantidad].Nombre = Console.ReadLine();
                    
                    Console.WriteLine("Contact's BirthDay:");
                    Contactos[Cantidad].Fecha = Convert.ToDateTime(Console.ReadLine());
                    Console.WriteLine("Contact's E-Mail:");
                    Contactos[Cantidad].Email = Console.ReadLine();
                    
                    Console.WriteLine("Número de contacto:");
                    Contactos[Cantidad].Numero = Console.ReadLine();
                    
                    Cantidad++;
                    Console.WriteLine();
                    
                }                    
                    
                else Console.WriteLine("¡Base de datos llena!:");
                break;
                case "2": Console.WriteLine("Usuario que desea buscar:");
                
                string buscar = Console.ReadLine();
                bool encontrado = false;
                for (int i = 0; i < Cantidad; i++) {
                    if (buscar.ToUpper() == Contactos[i].Nombre.ToUpper()) {
                        encontrado = true;
                        Console.WriteLine("{0}: Nombre: {1} Número: {2} E-Mail: {3} Fecha de nacimiento: {4}",i + 1, 
                        Contactos[i].Nombre,Contactos[i].Numero,Contactos[i].Email,Contactos[i].Fecha);
                    }
                    if(!encontrado)
                        Console.WriteLine("This Contact does not exist...{0}",!encontrado);
            
                }
                break;
                
                default: Console.WriteLine("Wrong!!!");
                Console.Clear();
                Console.ForegroundColor = ConsoleColor.DarkYellow; 
                Console.WriteLine();
                break;
            case "3": /*Me dá una lista de todas 
                      las personas que tengo agregadas.*/
                if (Cantidad == 0) {
                    Console.WriteLine("Data Base Empty!!!");
                }
                else
                
                for (int i = 0; i < Cantidad; i++) {
                    Console.WriteLine("Data Found:{0}",Contactos[i].Nombre);
                    
                    
                }
                
                
                break;
            case"4":
                if (Cantidad == 0) {
                    Console.WriteLine("Data Base Empty!!!");
                }
                else
                Console.WriteLine("type the contact you wish to delete...");
                for (int i = 0; i < Cantidad; i++) {
                    Console.WriteLine("Data Found:{0}",Contactos[i].Nombre);
                    
                    Console.WriteLine("Do you want to delete this data:");
                    Console.WriteLine("\nSelect one:");
                    string Delete = Console.ReadLine();
                    string Replace = string.Empty;
                    if (Delete == Contactos[i].Nombre) {
                        Console.WriteLine("Done:{0}",Replace.Replace(Contactos[i].Nombre,string.Empty));//It suppose to be deleted but not work at all.
                    }
                
                    
                }
                break;
            }
                Console.WriteLine("Logging out:");
                salir = Console.ReadLine();
            }
                while(salir!= "0");
            
            
                Console.ReadKey(true);
        }
    }
}