The example/demo scene is provided to show the asset working. The whole demo folder of the asset can be removed without breaking any other part of the asset. The exmaple data is also seperated from your data in the save editor window.
You can use the controls on the right hand side of the screen when in play mode to save, load or clear the data. To edit the data, enter text into the input fields on the left side, then press save data followed by load data to see the data loaded from the save with your changes.
The example scene controller script uses the API from the save manager to get the save object and apply the data from there, but you can also directly reference the scriptable object for the data and access it that way should you wish.