My system is macOS, I try to use /sbin/route to confing some custom route, I know 0.0.0.0 is the default ipv4 route, so I can delete/change/add the default ipv4 route by running route delete 0.0.0.0.
Then I searched wiki and I found the default route address of ipv6 is :: or ::/0, I try to delete the route by running route delete :: or route delete ::/0, It returns route: bad address: ::.
My ipv6 route table is:
Internet6:
Destination Gateway Flags Netif Expire
default fe80::3600:a3ff:fed3:93e5%en0 UGcI en0
default fe80::%utun0 UGcI utun0
::1 ::1 UHL lo0
The question is what is the default value and how I can change it?
In this case default means ::/0. When manipulating IPv6 routes with the route command don't forget to specify -inet6 so that it knows you're talking about the IPv6 routing table.
The following commands should all work for you:
sudo route delete -inet6 default
sudo route delete -inet6 ::/0
sudo route delete -inet6 default fe80::3600:a3ff:fed3:93e5%en0
sudo route delete -inet6 ::/0 fe80::3600:a3ff:fed3:93e5%en0
They should all remove the default IPv6 route entry from your en0 interface.