To view all the background pictures you have used:

1. Right-click any blank areas on the desktop and select Personalise.

2. Set Background to Picture and you will see all the background pictures that you have used.

Perform the following operations to delete these pictures. Note: This operation involves modifying the registry list. Please be careful and consult a professional when doing this.

1. Press the Win and R keys at the same time to display the Run window. Enter regedit and click OK.

2. Enter HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Wallpapers in the Registry Editor. All previously used desktop background pictures will be displayed in the right window, arranged from 0 to 4.

3. Right-click the background picture you want to delete and select Delete.

4. Click Yes in the pop-up dialog box.

5. When you go to set your background picture you will find that it is no longer there under Picture.
   

   Background pictures that are preinstalled in the Windows system cannot be deleted, you can only delete pictures displayed under Picture.