When I type something in Thunderbird's search bar, the first item that pops up is a Bing search for that term. Is there a way to remove Bing? I don't really need Thunderbird to be able to search the web.

So just removing it and leaving nothing is acceptable, but replacing it with, say, Google (or anything that's not Bing) works as well. I perused all the settings dialogs and preferences and couldn't find anything of the sort.