To uninstall your AVG antivirus, you can use the AVG Remover tool from the AVG Technologies web page. If you're using Windows Vista, Windows 7 or Windows 8, right click on the application and select Run as Administrator. After the process is complete, restart your computer and manually remove the following folders:
For Windows XP:
C:\Program Files\AVG or C:\Program files(x86)\AVG (for 64bit OS)
C:\Documents and settings\All users\Application data\AVG8
C:\Documents and settings\All users\Application data\AVG9
C:\Documents and settings\All users\Application data\AVG10
C:\Documents and settings\All users\Application data\AVG2012
C:\Documents and settings\All users\Application data\MFAData
For Windows Vista/7/8:
C:\Program Files\AVG or C:\Program files(x86)\AVG (for 64bit OS)
C:\ProgramData\AVG8
C:\ProgramData\AVG9
C:\ProgramData\AVG10
C:\ProgramData\AVG2012
C:\ProgramData\MFAData
C:\Users\<user>\AppData\Roaming\AVG8
C:\Users\<user>\AppData\Roaming\AVG9
C:\Users\<user>\AppData\Roaming\AVG10
C:\Users\<user>\AppData\Roaming\AVG2012