Unable to remove Bing from Safari on MacBook Air

Go to Safari Settings > Search > and select a different Search engine, Google or DuckDuckGo, for example.

Change Search settings in Safari on Mac - Apple Support

Removing "Search Marquis" / "Search Baron" / etc on your own - Apple Community may be applicable. The reason for my suspicion is explained it its introduction:

All of a sudden Safari began redirecting all your search queries or clickable links to results you did not expect, rudely ignoring your desired Search engine preferences. Those search results or web pages may show "Search Baron" or "Search Marquis" or "Search Now" or Bing or Yahoo or any number of other possibilities... none of which are what you want.

(emphasis added)

If you think that describes your concern, follow those instructions, or ask for help.

Change the default web browser or email app on Mac - Apple Support may also be applicable.