Let me REMOVE items from library

I'm aware of the reasons collection was replaced by library, and although I disagree with the direction of the feature, this is not me trying to debate it.

However, I have now been stuck for months with items in my custom library (from when it was still collection) and I literally cannot remove any of those items even though I no longer own some of them. It's driving me mad. What's the point in even allowing and showing the custom library tab if it can't be edited?