windows 7 - Virus Infection; Now I'm trying to delete folders from Program Files

AVG seems to have quarantined the two Trojan malware but I can't delete the folders:

Program Files > Google > Desktop > Install > {string of numbers}

Changing Ownership and Permissions doesn't do anything except get Windows Explorer rebooting. Or, there's a pop-up message saying access is denied.

There's a Lock icon on the top, Google, folder.

Has anyone found a way to delete a rooted-in folder in Program Files?

Thanks

Update: The advice was overwhelming to reinstall the OS, so I did that. I backed-up only file formats that were safe, like .odt, .jpg, .avi or .mpg. Those went to a different hard drive and I ran two checks of those files with AVG.
Then I performed a clean install which first formatted the infected drive.
So far so good, and thanks, everyone, for taking the time to lend advice.

P.S.
I was certain this wasn't a duplicate question because I searched for other references to that string of folders: Google > Desktop > Install... Search didn't reveal any references to it. So I asked how to remove that Folder and its contents.
I may have received a duplicate solution to the problem -- format and start over -- but I didn't see a duplicate of my question.