The default set up you are handed after running Blender will give you:

• Camera
  
• Light source
  
• Cube

These objects are placed to look generally like a small studio room.

It called your mom stinky.

Before touching anything, tap the "A" button on your keyboard twice. Once to deselect whatever is currently selected by default, and once more to select everything in the scene.
Next, press the "X" button to delete everything highlighted in your selection.
All you need to do now, is confirm your selection. This will complete the deletion and allow you to start a brand new project.