Remove DuckDuckGo from Safari? Sonoma

Your question is not clear to me. DuckDuckGo is a search engine, a website, an app, a Safari Extension, a privately held company... perhaps others. Which one are you referring to?

Writing an effective Apple Support Communities question - Apple Community

If you prefer to use a different Search Engine for Safari, follow IdrisSeabright's instructions:

Change Search settings in Safari on Mac - Apple Support

Do you mean you want to use a different default search engine? If so, see here:

Change Search settings in Safari on Mac - Apple Support

If you mean something else, please explain.