The question of why apps/other things ask for privilege when we are logged in as administrator can be hard on folks new to operating systems. Here it is. Take time to ponder.
"There is no God mode in Windows."
Even an administrator must obey permissions. An administrator can change permissions so it's not as if you don't have the power to do what you want (short of some OS protected areas.)
I see AVG Forums do have discussions about manually removing AVG.
I'm a recent user of Win 8.1 (new i7-4770K desktop), and I'm really pleased with this system. Problem: I installed a freeware app which also installed AVG SafeGuard toolbar. The AVG software nuked the Google toolbar and my preferred homepage. I tried to remove the AVG software with Win 8.1 Uninstall Program in Control Panels with no success. The AVG ScriptHelper just hangs. When the session is closed I receive the message that running uninstaller requires administrator privilege. I'm logged in as administrator. Any tips on how to remove this obnoxious software is welcome. Thanks.