Delete
Reference
Mode:
Object Mode
Menu:
Object ‣ Delete
Shortcut:
X or Delete
Delete the selected objects from the current scene.
Delete Globally
Reference
Mode:
Object Mode
Menu:
Object ‣ Delete Globally
Shortcut:
Shift-X or Shift-Delete
Delete the selected objects from all scenes, and any other possible usages (like e.g. from a shading node).