After installing Windows 10, you might be one of those hopeful to see the new desktop wallpaper image Microsoft provided that was created with light, lasers, and projectors, but it's just not displaying for you. Or, maybe you want to turn off the background image altogether because it's just too distracting.

 

The location for turning the background image on and off is located in the Ease of Access settings.

 

To get there:

 

1. Open the Notification Center in the Windows 10 System Tray and click or tap the All Settings tile.
    
   
    
    
    
   
2. When the Settings window (formerly called the Control Panel) displays, choose Ease of Access.
    
   
    
    
    
   
3. On the Ease of Access window, navigate down to Other Options and then locate the Show Windows Background toggle switch.
    
   
   

Source : winsupersite

I actually like the new background image that showed up in the last build. My old background was dated and this is a nice change.