På engelska, med bilder; http://www.fettesps.com/how-to-uninstall-bing/
Det verkar inte helt lätt;
"on windows xp
I found it was the updates that put bing as default
so I uninstalled the updates. To do so
Carefully select and then copy the following command:
Click Start, and then click Run.
In the Open box, type Cmd.exe, and then press ENTER.
Right-click inside the Cmd.exe window, and then click Paste to paste the command that you copied in step 1.
Press ENTER to uninstall Internet Explorer 8.
When the uninstall program is finished, restart your computer."