Admins can create/edit and delete users (with all their projects etc.)
Deleting a user/project/visualization automatically deletes all its belonging
data (e.g. deleting a visualization deletes all plots).
When creating and deleting objects the relationship is (mostly) handled server
side. Only the first required relationship (e.g. when creating a new project,
the project's owner is set client-side, the rest is matched on the server).
