Robdar, this was probably a simple misunderstanding. I totally agree with you that letting go (or refusing) existence wouldn't be right. But it can be quite helpful to conciously let go of an unwanted emotion (like anger) in a certain situation.
For example can I become very upset about what somebody says to me. Now I have two possibilities: I can stay in that upset mood and maybe give a heated answer that I would probably regret later on or I can decide to let go of the anger and to calm down. Would you consider anger a blessing emotion or mood that you would love to stay in for as long as possible? In my opinion it's ok to acknowledge being angry but I don't want to stay in that mood forever because it makes me feel bad and unable to enjoy my day the way I want to. Letting go in that sense means the same as saying: "What the hell!"
Of course, the best way of life would be to never feel a desire to get angry or upset about what other people say or do. But I have to admit I am still working on this one!