Which Configuration to Use?

CIS provides three Configurations, i.e. Internet, Proactive and Firewall. Which should one use for day-to-day use? How does one remove the Antivirus component to prevent possible clashes with existing Antivirus software?

You don’t have to remove AV.
Just disable it and later you can use it as a 2nd opinion on-demand scanner.
Internet Security mode is default but I would recommend Proactive cause it warns you about unknown outbound traffic (trusted apps are silently allowed).