Where does Mac OS X save the list of items/icons it shows in the Finder sidebar?
The Finder Sidebar is defined in ~/Library/Preferences/com.apple.sidebarlists.plist. It may be stored in binary. If you have a property list editor, this won't matter; if you don't, you'll want to convert it to XML first:

plutil -convert xml1 ~/Library/Preferences/com.apple.sidebarlists.plist


Then, open it in a text editor. There's probably an entry like so in there:

&lt;dict&gt;
    &lt;key&gt;Icon&lt;/key&gt;
    &lt;data&gt;…&lt;/data&gt;
    &lt;key&gt;CustomItemProperties&lt;/key&gt;
    &lt;dict&gt;
        &lt;key&gt;com.apple.LSSharedFileList.TemplateSystemSelector&lt;/key&gt;
        &lt;integer&gt;1935819892&lt;/integer&gt;
    &lt;/dict&gt;
    &lt;key&gt;Name&lt;/key&gt;
    &lt;string&gt;Desktop&lt;/string&gt;
    &lt;key&gt;Alias&lt;/key&gt;
    &lt;data&gt;…&lt;/data&gt;
&lt;/dict&gt;
&lt;/plist&gt;


(Note the key Name with string value Desktop.)

Delete that whole &lt;dict&gt; node, and save.