It seems you can't reuse a library once it is live/published to production. Since I don't want to keep creating new libraries when I am experimenting, what I do is promote to the Staging/Submitted stage (not to production), then reject it if I need to make a change. And keep recycling the same library that way rather than creating a proliferation of libraries. I hope this helps.

Thanks @mikewebguyThis helps.

Thanks Gigazelle​.Will do so.