If you have disabled an IPv6 tunnel using the netsh command-line tool, the IPv6 interface will be successfully removed. However, the client will continue to register that interface's IPv6 address with the DNS server until the server is rebooted.
To work around this issue, simply stop and restart the dnscache service (DNS Client service). This service is the one that actually registers names with the DNS server. Restarting it will cause it to re-inventory the interfaces and stop uploading old data.
This allows you to fix this situation on servers without having to fully reboot them.