DeleteNamespace
Use the DeleteNamespace API operation to delete a namespace 
                 and the users and groups that are associated with the namespace. This is an asynchronous process. Assets including dashboards, analyses, datasets, and data sources are not deleted. To delete these assets, you use the relevant API operations for each asset, such as DeleteDashboard or DeleteDataSet.
Following is an example AWS CLI command for this operation.
For more information about the DeleteNamespace API operation, see DeleteNamespace in the Amazon Quick Sight API Reference.