IMac Very slow to respond EtreCheck Report - Please Help

To start with, two problems:

You gave a super snail speed 5400 rpm spinning drive which does everything super slow, the easiest remedy would be to get an external SSD, format it and clone your entire system to it and then run your computer from that, You can then use the internal drive as extra storage.

You have Clean My Mac installed. It is of little use and may contribute to problems. Go to their website and get uninstall instructions and uninstall it. Reboot and enjoy your Mac.

Your current iMac will never be fast as it is a base model, the primary bottleneck is the 5400 RPM HD that is installed. You have also made matters worse by installing CleanMyMac which is considered malware by experienced users. I would recommend locating the developers uninstall instructions for CMM and follow them to the letter. Then restart the computer in Safe Mode and test.

As for the HD, rather than attempting to fix that situation I would consider replacing the computer with a new 24" with 16GB of RAM and the highest capacity SSD you can afford. If you insist on keeping the computer the ONLY thing that will make it faster is to buy an external USB 3 SSD and then clone the internal HD to the new SSD and use the SSD as your boot drive.

If you mean can you erase the computer and start all over again as if it was new with no personal data on it, yes you can. If you mean something else please be as specific as you can so we can advise.

If you choose to do this PLEASE do ensure you have a current Time Machine backup of your system. THIS IS CRITICAL!!!!