you can simply press the cross next the the "pop up".
I usually save when I see one of these and if it's an event that is a net - in favor I simply reload and close the popup (only exception being the training one which give extra stamina, but it's usually well perceived)

That's true. But if I have more than 2 followers, then usually I get 50% decrease and 50% increase. That's the problem I have. And if I just cancel, then a few in game days later, I'll see one of my followers decreased by 10-20 points for no reason.