How do I remove or edit custom ranges on a slider?

How do I remove or edit custom ranges on a slider?

I have added some ranges to a slider, but have realised that I either made a mistake or want to edit what I created. I do not see how I can do this. I can add a new one and deselect the incorrect one, but would be nice to keep the area clean and tidy and not have non useful options.

Thanks

Steve