Как сделать проверку на наличие пользователя по паролю? - C#

if (password != passwordfind)
{
Console.WriteLine(" Пользователя с таким паролем не существует")
}

using System;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.Threading;
namespace ConsoleApplication1
{
    public class User
    {
        public string name;
        public string surname;
        public string country;
        public string sex; //male or female 
        public int age;
        public string mail;
        public string login;
        public decimal password;
        public User(string name, string surname, string country, string sex, int age, string mail, string login, decimal password)
        {
            this.name = name;
            this.surname = surname;
            this.country = country;
            this.sex = sex;
            this.age = age;
            this.mail = mail;
            this.login = login;
            this.password = password;
        }
 
    }
    public class server
    {
        public string name;
        public string coutry;
        public string ip;
        public List<string> Servers = new List<string>();
 
    }
    class Program
    {
 
        public static void changePassword()
        {
            Console.WriteLine("Enter your password");
            string Pass = Convert.ToString(Console.ReadLine());
            Console.WriteLine("Enter your new password");
            string firstPass = Convert.ToString(Console.ReadLine());
            if (Pass == firstPass)
            {
                do
                {
                    Console.WriteLine("Your new password is the similar as your old one");
                    Console.WriteLine("Enter your new password");
                    firstPass = Convert.ToString(Console.ReadLine());
 
                }
                while (Pass == firstPass);
            }
            Console.WriteLine("Enter your password one more time");
            string secondPass = Convert.ToString(Console.ReadLine());
            string lastPass;
            if (firstPass != secondPass)
                do
                {
                    Console.WriteLine("It wasn't correct with you new pass! Enter your password one more time");
                    lastPass = Convert.ToString(Console.ReadLine()); ;
                }
                while (firstPass != lastPass);
            Console.WriteLine("Your password successfully saved");
        }
        public static void changeLogin()
        {
            Console.WriteLine("Enter your login");
            string log = Convert.ToString(Console.ReadLine());
            Console.WriteLine("Enter your new login");
            string firstLog = Convert.ToString(Console.ReadLine());
 
            if (log == firstLog)
            {
                do
                {
                    Console.WriteLine("Your new login is the similar as your old one");
                    Console.WriteLine("Enter your new login");
                    firstLog = Convert.ToString(Console.ReadLine());
 
                }
                while (log == firstLog);
            }
            Console.WriteLine("Enter your new login one more time");
            string secondLog = Convert.ToString(Console.ReadLine());
 
            string lastLog;
            if (firstLog != secondLog)
            {
                do
                {
                    Console.WriteLine("It wasn't correct with you new login! Enter your login one more time");
                    lastLog = Convert.ToString(Console.ReadLine());
                }
                while (firstLog != lastLog);
            }
            Console.WriteLine("Your login successfully saved");
 
        }
        public static void dataLogin()
        {
            changeLogin();
            changePassword();
        }
        public static void Greeting()
        {
            Console.WriteLine("Hello, dude!");
        }
 
        static void Main(string[] args)/////////////////////////////////////////////////////////////////////////////////
        {
            Greeting();
            Console.WriteLine();
            User User1 = new User("Vlad", "Seleznev", "Ukraine", "Male", 17, "removed@mail.ru", "Seleznev12", 12345);
            User User2 = new User("Ruslan", "Molchanuk", "Ukraine", "Male", 18, "risegaming.com", "rise12", 123456);
            User User3 = new User("Alexander", "Aprelenko", "Estonia", "Male", 17, "qwerty.com", "apr12", 1234567);
            User User4 = new User("Andrey", "Tsaryk", "Ukraine", "Male", 21, "sayta.net", "and12", 12345678);
            User User5 = new User("Patrik", "Buravchuk", "Ukraine", "Male", 16, "negrinafiji.net", "pat12", 123456789);
            User User6 = new User("Vetrov", "Alexey", "Ukraine", "Male", 17, "vetroveletel.est", "vet12", 12);
            User User7 = new User("Alexandra", "Suvorova", "Ukraine", "Female", 18, "s.suvorova98", "suv12", 123);
            User User8 = new User("Piven", "Bogdan", "Ukraine", "Male", 16, "pityxi.com", "bog12", 1234);
            User[] UsersArray = { User1, User2, User3, User4, User5, User6, User7, User8 };
            List<User> UsersList = UsersArray.ToList();
 
            foreach (User i in UsersList)
            {
                Console.WriteLine(i.name + " " + i.surname + " " + i.country + " " + i.sex + " " + i.age + " " + i.mail + " " + i.login + " " + i.password);
                Console.WriteLine("-------------------------------------------------------------------------------");
            }
            Console.WriteLine();
            // dataLogin(); 
 
            Console.WriteLine("Введите пароль пользователя для удаления");
            decimal passwordfind = Convert.ToDecimal(Console.ReadLine());
            User use = UsersList.FirstOrDefault(x => x.password.Equals(passwordfind));
            UsersList.Remove(use);
            foreach (User i in UsersList)
            {
                Console.WriteLine(i.name + " " + i.surname + " " + i.country + " " + i.sex + " " + i.age + i.mail + " " + i.login + " " + i.password);
                Console.WriteLine("-------------------------------------------------------------------------------");
            }
            Console.WriteLine();
 
            Console.ReadKey();
        }
    }
}