If just 2 percent of users donated to Blender, we could support more developers to work on tools and make it the best 3d software, free for everyone, forever!
Reference
Object Mode
Object ‣ Delete
X or Delete
Delete the selected objects from the current scene.
Object ‣ Delete Globally
Shift-X or Shift-Delete
Delete the selected objects from all scenes, and any other possible usages (like e.g. from a shading node).