Powershell com direitos de administrador
Tente excluir IP6Tunnel
netsh interface ipv6 delete interface IP6Tunnel
ou
Mostrar endereço IP: netsh interface ipv6 show address
Apagar ip / use Nome da interface: netsh interface ipv6 delete address Ethernet0 200x:x:x:x:x:x:x:x
netsh interface ipv6 delete address (Índice ou nome da interface) (ipv6address)
Mostrar rotas: netsh interface ipv6 show route
Excluir rota: netsh interface ipv6 route delete 200x:x:x:x::/64 Ethernet0 store=persistent
netsh interface ipv6 rota delete (ipv6prefix :: / 64) (Índice de Interface ou Nome)