Events with anonymous delegate

I subscribed to an event with an anonymous delegate. Later I was in need for a solution to be able to unsubscribe this delegate. This is a simple solution for the problem:

public class ClassName

{

    MouseButtonEventHandler eventHandler;

    public ClassName()

    {

        eventHandler = delegate

                                        {

                                            // operations

                                        };

    }

    void Functionality()

    {

        if (_subscribe)

        {

            _object.MouseLeftButtonDown += eventHandler;

        }

        else

        {

            _object.MouseLeftButtonDown -= eventHandler;

        }

    }

}