Listbox item Context Menu WPF and MVVM

I have tried a lot of solutions but non of them work for me. I am using WPF and MVVM.

I have the following XAML file

Available Items

And I have my MainPresenter class

   private ItemModel _selectedItem;
   public ItemModel SelectedListItem
   {
            get => _selectedItem;  
            set
            {
                if (Equals(_selectedItem, value)) return;
                _selectedItem= value;
                RaisePropertyChangedEvent("SelectedListItem");
            }
        }
    public IEnumerable ItemsList=> _dataStore.GetItems();
    public ICommand RemoveSelectedItem()
    {
       return  new RelayCommand(RemoveSelectedItemFromList);
    }
    private void RemoveSelectedItemFromList(ItemModel item)
    {
            MessageDialogs.ShowInfoMessage(item.Name);
     }

What could be wrong, I have tried almost everything. I guess that the problem is with DataContext, but how to fix it ?