SomeCode

namespace ConsoleApp1
{
    public class StartUp
    {
        public static void Main()
        {
            MyClass myClass = new MyClass();

            ChangeMyClassNameProp(myClass);
            // myClass.Name == "Changed"

            SetMyClassToNull(myClass);
            // myClass != null
        }

        private static void ChangeMyClassNameProp(MyClass myClass)
        {
            myClass.Name = "Changed";
        }

        private static void SetMyClassToNull(MyClass myClass)
        {
            myClass = null;
        }
    }

    public class MyClass
    {
        public string Name { get; set; }
    }
}