How to uninstall when the application, AVG Antivirus is not open!

Hello Hideo. 
Thank you for your patience.
Regarding the Preferences file, we'd like to confirm that it is completely different from ApplicationSupport folder. We'd never recommend to delete any information from Preferences folder concerning AVG uninstallation. 
If you need any further clarification, please specify your request in detail.

Hello Hideo,

We are sorry to know this.
We request you to refer to this article: https://bit.ly/38WvkK3 to uninstall AVG AntiVirus free from your Mac system.
After that, you can try to reinstall AVG program.
Thank you.

I use iMac on MacOS High Sierra. I have used  AVG antivirus free application. But recentley this application is not open. Thus this application can not be uninstalled. Therefore new version of this application cannot be installed. How do I uninstall this unopen application? I have no answer from AVG Customer Care  to request how to do.
Hello Sivakumar,

I deleted the AVG folder in the hidden folder by the above procedure, but I still get an Installation Error with the following message, ”AVG Antivirus is already installed, please uninstall the previous version first.”  Please help me !

Hello Hideo. 
Thank you for your patience.
Regarding the Preferences file, we'd like to confirm that it is completely different from ApplicationSupport folder. We'd never recommend to delete any information from Preferences folder concerning AVG uninstallation. 
If you need any further clarification, please specify your request in detail.

We'll certainly check & clarify this for you, Hideo.

Both AVG & Avast Antivirus are the same, they use the same virus definitions database & have the same features. They just have different user interfaces.
Regarding your query about Mac preference file, we've escalated your case to our higher level of support.
Once we receive an update from them, we'll write back to you in this post.
Meanwhile, your patience is very much appreciated.
Thanks!

I do not know why the second try was sucess. I remembered the preference file was important in old mac when problems occurred. So I searched the preference file but I could not find it. I do not know the file is invisible. However you teach me the file in the library and Application support. This file is different from preference file. This is a big discovery.

By the way, would you please teach me the difference between AVG Antivirus and AVAST Antivirus?
Hello Hideo,

We are sorry to know this.
We request you to refer to this article: https://bit.ly/38WvkK3 to uninstall AVG AntiVirus free from your Mac system.
After that, you can try to reinstall AVG program.
Thank you.
Glad to hear that, Hideo.
Feel free to reach us if you face any difficulties with AVG.
Stay safe and healthy!!