Удалить TabItems по клику на Button через UserControl

TabItem thistabitem = this.tabs.SelectedItem as TabItem;

 public class RelayCommand : ICommand
    {
        readonly Action _execute_with_param;
        readonly Action<object> _execute;
        readonly Predicate<object> _canExecute;
 
        public RelayCommand(Action<object> execute) : this(execute, null) { }
        public RelayCommand(Action execute) : this(execute, null) { }
 
        public RelayCommand(Action<object> execute, Predicate<object> canExecute)
        {
            if (execute == null)
                throw new ArgumentNullException("execute");
 
            _execute = execute;
            _execute_with_param = null;
            _canExecute = canExecute;
        }
 
        public RelayCommand(Action execute, Predicate<object> canExecute)
        {
            if (execute == null)
                throw new ArgumentNullException("execute");
 
            _execute = null;
            _execute_with_param = execute;
            _canExecute = canExecute;
        }
 
        public event EventHandler CanExecuteChanged
        {
            add { CommandManager.RequerySuggested += value; }
            remove { CommandManager.RequerySuggested -= value; }
        }
 
        public bool CanExecute(object parameter)
        {
            return _canExecute == null ? true : _canExecute(parameter);
        }
        public void Execute(object parameter)
        {
            if (_execute != null)
                _execute.Invoke(parameter);
            if (_execute_with_param != null)
                _execute_with_param.Invoke();
        }
    }

TabItem thistabitem = this.tabs.SelectedItem as TabItem;