Virus warning

You are welcome, my friend. But please understand that taking the above steps is no guarantee that your Mac is now completely safe, free of malware, and out of reach of that person. As I said earlier, being as you gave that person remote access to your machine, you have no idea what they may have surreptitiously installed on it. As such, you have no idea where to look for it, if it exists, and even Malwarebytes and similar apps may not be able to detect it. In the end, if you continue to notice weird behavior on your machine -- anything that does not seem right -- you need to reformat your hard drive and reinstall Mojave from scratch. In other words, don't just reinstall Mojave over top of your current installation. Erase your hard drive first to rid it of any vestiges of what that person may have done on your machine. It's better to play it safe.

... is that a service provided by Apple?

No. You were defrauded.

Refer to Phony "tech support" / "ransomware" popup… - Apple Community.

He needs to erase his drive and reinstall. That should remove MacCleaner don't you think?

FWIW, removing Mac Cleaner is the least of the user's problem. He/she already gave out payment information and allowed the scammers access to his computer. You should read the link John provided.

Dialabrain, I know that. But please take note that I already mentioned the remote access danger to him in my first comment above. However, he still needs to remove Mac Cleaner from his hard drive before it causes further damage. I have explained to him how he can do that. Or do you think he should just leave it on there? I didn't think so. :)

And, of course, he should read John's info on the other page as well. My comments do not in any way negate John's comments. I believe that the idea behind this community is to provide different perspectives regarding the plethora of issues which arise here. Collectively, a person can gain a wide range of info, and then act accordingly to resolve their issue. No one knows it all, or has all the answers, so it should be a community effort; don't you agree?

Great! Hopefully, your Time Machine backup was not affected by this. I wish you the best. :)

Oh, gosh, my friend. I feel so sorry for you. You were just majorly scammed. That particular scam appears all over the web, particularly when visiting questionable websites -- like torrent sites and hacked software sites, for example. It was a major mistake on your part to not only purchase the bogus software, but even worse, to give some unknown stranger remote access to your machine. Who knows what they may have already put on it. I suggest that you immediately run some trojan and virus scanning software on your machine, and hope that said persons haven't already dug in too deeply. And, no, that is most definitely NOT a service provided by Apple. Let me know how it goes. Thanks!

Following are the steps you can follow to manually remove Mac Cleaner from your hard drive. There are apps out there which will do the same thing, but doing it manually will ensure that you've found and removed most, if not all, of the malicious files which are related to Mac Cleaner:

1. Shut down Mac Cleaner if it is currently running on your Mac.

2. To verify that Mac Cleaner -- or Advanced Mac Cleaner -- is truly shut down, use the "Activity Monitor" app, which is found in /Applications/Utilities. Look for the names "Mac Cleaner" and "Advanced Mac Cleaner" in the processes list, and then quit them.

3. In the "Apple" menu, "System Preferences" from the dropdown menu.

5. When the "System Preferences" window opens, click on the "Users & Groups" prefs pane.

6. When it opens, select your username in the list on the left side of the window.

7. Click on the "Login Items" tab on the right side of the same window.

8. Using the minus button near the bottom of the window, select and remove any items which appear to be related to "Mac Cleaner" or "Advanced Mac Cleaner.

9. Next, go to /Library/LaunchAgents. This is the MAIN Library folder that is located at the top level of your hard drive, and not your user Library in your Home folder.

9. Once you are in the "LaunchAgents" folder, look for any files that have the following names, or very similar names:

com.AdvancedMacCleaner.agent.plist

com.AMC.agent.plist

com.AMC.amchlpr

10. Move each file that you find to the Trash. Enter your administrator password if requested to do so.

11. Next, go to ~/Library/LaunchAgents. This is the Library that is in your Home folder.

12. Search for the same files, or similarly-named files, that I listed in step 9.

13. Next, go to ~/Library/Application Support. This folder will be near the top of your Home Library.

14. In the "Application Support" folder, look for the following files, or similarly-named files, and likewise move them to the Trash:

Advanced Mac Cleaner

helperamc

hlpramc

hlprawc

hlpramcn

hlpradc

Mac Adware Cleaner

15. The above steps should hopefully remove all of Mac Cleaner -- or Advanced Mac Cleaner -- from your hard drive. As an added post-deinstallation step, you may want to run a malware detection app such as Malwarebytes for Mac.

I hope the above info has been beneficial to you. Please let me know. Thanks!