I think what I'm trying to do is very simple but I can't manage to

I have a static event somewhere in a class A:

```
public static event Action OnInvalidated;

```

that I call when my data is invalidated.
When I instanciate a new class of type B, I want to do the following:

```
A.OnInvalidated+= () => this.RefreshColumns();

```

Basically I want to call RefreshColumns on every instance registered when OnInvalidated fires.

This compiles fine, but how can I remove the lambda function when I dispose of my object?
I think that doing 

```
 A.OnInvalidated-= () => this.RefreshColumns();

```

Will not work, and I can't declare

```
Action myAction = () => this.RefreshColumns();

```

as a function member either