Since so many others are having trouble removing Avira antivirus program I thought I would post this solution that worked for me. First of all, I use Win Vista program removal program but this left the Avira program folder intact on the C drive. Every time I tried to remove it I got the Destination Folder Access Denied dialog with the error "I need permission to perform this action". I changed permissions for all the files and folders in the Avira program folder, but still got the error!!! (any one know why this happens so frequently in Win Vista?).
What finally worked was that I reinstalled Avira again and rebooted. Then I ran the Avira installer again but chose the option to remove all components. This worked! All traces were removed. I then ran CC Cleaner to make sure. Hopefully, this also stops the pop up to buy the product.