Erm, what do you mean PC is in compatibility mode? Compatibility mode is a per-program setting or am misunderstanding something?
If you mean that those programs are running in compatibility mode and you can't turn it of, look here in the registry
HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers
and find the entries for the programs and simply delete them.