how to remove search marquis from my mac pro

Hi 2648-jhs,

Thank you for participating in the Apple Support Communities. We understand you'd like to remove and keep malware off your Mac. This article has some information which you may find helpful: Block pop-up ads and windows in Safari.

"If adware or other unwanted software is installed on Mac

If you see pop-ups on your Mac that just won’t go away, you might have unintentionally downloaded and installed adware (advertising-supported software) or other unwanted software. Certain third-party download sites might include software that you don’t want along with the software that you do.

If you think that you might have malware or adware on your Mac:

• Update to the latest version of macOS. If your Mac is already using the latest version, restart your Mac. macOS includes a built-in tool that removes known malware when restarting.
• Check your Applications folder to see if you have any apps that you don't expect. You can uninstall those apps.
• Check the Extensions tab in Safari settings to see if you installed any unnecessary extensions. You can turn extensions off.

If you continue to see advertising or other unwanted programs on your Mac, contact Apple."

This article has some helpful information as well: Protect your Mac from malware.

Protect your Mac from malware

macOS has many features that help protect your Mac and your personal information from malicious software, or malware. One common way malware is distributed is by embedding it in a harmless-looking app.

You can reduce this risk by using software only from reliable sources. Privacy & Security settings allow you to specify the sources of software installed on your Mac.

1. On your Mac, choose Apple menu  > System Settings, then click Privacy & Security  in the sidebar. (You may need to scroll down.)
2. Go to Security, click the pop-up menu next to “Allow applications downloaded from,” then choose the sources from which you’ll allow software to be installed:

• App Store: Allows apps only from the Mac App Store. This is the most secure setting. All the developers of apps in the Mac App Store are identified by Apple, and each app is reviewed before it’s accepted. macOS checks the app before it opens the first time to be certain it hasn’t been modified since the developer shipped it. If there’s ever a problem with an app, Apple removes it from the Mac App Store.
• App Store and identified developers: Allows apps from the Mac App Store and apps from identified developers. Identified developers are registered with Apple and can optionally upload their apps to Apple for a security check. If problems occur with an app, Apple can revoke its authorization. macOS checks the app before it opens the first time to be certain it hasn’t been modified since the developer shipped it."

Take care.

Please read Removing "Search Marquis" / "Search Baron" / etc on your own - Apple Community, and post the three screenshots it describes in a reply to this Discussion.