Security: How to ensure that a malware has been completely removed from MacOS?

Recently, I downloaded Photoshop Downloader and the installer seemed very suspicious. I was completely out of my mind while proceeding with the installation and a pop-up window asked me for permission to make changes in which I pressed OK. However, I realized that it was probably malware because, once it was finished, Google Chrome was closed and when I opened it again, it changed the search to the Search tab.

I wanted to delete all these files, so I executed malware bytes. The analysis came back with some threats that I was familiar with and I immediately eliminated them from quarantine.

A few days later, I saw another 2 permission pop-up windows that asked me to access and modify the settings, and immediately rejected and pressed "Do not allow." I did another scan and I found threats again and they were stored in quarantine. I analyzed these and found binary code / html readable and binary suspicious. One of the file names was "com.9cu4m" and I tried to make nano in the file to read the code, but it was unreadable

I destroyed them, removed them and destroyed them using gshred but I'm still paranoid that there are files in the system that can do something. Is there any way to verify that these threats / files or similar files no longer exist in my system and how to prevent this in the future?