To manage your visualizations, log in to Superchart and navigate to My Visualizations. From there, you can take a few actions:
In your gallery of visualizations, you can easily see which visualizations are currently published and which are unpublished via the icon. Green icon = published; grey icon = unpublished.
Creating a variation of a visualization or using an existing visualization as a starting point is easy. You can duplicate a visualization from the My Visualizations page.
For visualizations that are published, you can grab the embed code for the visualization here easily as well.
Use the three-dot menu on an individual visualization to delete it permanently.
You'll need to confirm the deletion, just to ensure you're ok wiping out the visualization entirely.