Removing Search Marquis from Macbook Air without the use of anti-malware programs

I have been struggling with search marquis on my macbook air (early 2014, updated with Catalina OS) and I've been told it is possible to remove it simply and without the use of any anti-malware program. The search marquis by the way appears in Chrome, Safari as well as Firefox. I sincerely hope someone can help me to remove it manually and for good (in particular I'm thinking about John Galt who wonderfully helped ResetR to remove search marquis around November 2020).

I took screenshots of the following folders:

~/Library/LaunchAgents

/Library/LaunchDaemons

/Library/LaunchAgents

~/Library/LaunchAgents

/Library/LaunchDaemons

/Library/LaunchAgents

I hope someone can help me and tell me what I can or should delete from these folders.

Thanks