MainWindow.xaml.cs:

    using System;
    using System.Collections.ObjectModel;
    using System.ComponentModel;
    using System.Windows;
    using System.Windows.Input;
    namespace ComboboxItemWithButton
    {
      public partial class MainWindow : Window
      {
        public MainWindow()
        {
          InitializeComponent();
         
        }
      }
      public class ViewModel : INotifyPropertyChanged
      {
        public ViewModel()
        {
          for(int i = 0; i < 5; i++)
          {
            books.Add(new BookEntry( $"BOOK{i}", "Visible"));
          }
         
        }
    
        private ICommand _myCommand;
        public ICommand MyCommand => _myCommand ?? (_myCommand = new RelayCommand(parameter =>
        {
          if (parameter is BookEntry v)
          {
            Books.Remove(v);
            MessageBox.Show(Books.Count.ToString());
          }
        }));
        private ObservableCollection<BookEntry> books = new ObservableCollection<BookEntry>();
        public ObservableCollection<BookEntry> Books
        {
          get { return books; }
          set { books = value; OnPropertyChanged("Books"); }
        }
        private BookEntry selectedItem ;
        public BookEntry SelectedItem
        {
          get { return selectedItem; }
          set {
            if (selectedItem == value) return;
            selectedItem = value;
            selectedItem.ISShow = "Hidden";
         
            OnPropertyChanged("SelectedItem"); }
        }
        private void OnPropertyChanged(string propertyName)
        {
          if (PropertyChanged != null)
            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
        public event PropertyChangedEventHandler PropertyChanged;
      }
      public class RelayCommand : ICommand
      {
        private Action<object> execute;
        private Func<object, bool> canExecute;
    
        public event EventHandler CanExecuteChanged
        {
          add { CommandManager.RequerySuggested += value; }
          remove { CommandManager.RequerySuggested -= value; }
        }
    
        public RelayCommand(Action<object> execute, Func<object, bool> canExecute = null)
        {
          this.execute = execute;
          this.canExecute = canExecute;
        }
    
        public bool CanExecute(object parameter)
        {
          return this.canExecute == null || this.canExecute(parameter);
        }
    
        public void Execute(object parameter)
        {
          this.execute(parameter);
        }
      }
     
      public class BookEntry
      {
        public string Name { get; set; }
        public string ISShow { get; set; }
        public BookEntry() { }
        public BookEntry(string name, string show)
        {
          Name = name;
          ISShow = show;
        }
        public override string ToString()
        {
          return Name;
        }
      }
    }