I can successfully delete IPv4 DNS Servers via command line on a Windows Server 2019 with the following command:
netsh interface ipv4 delete dnsserver "My Ethernet" all
After this command I execute ipconfig /all
and see the following IPv6 DNS Servers show up (which were not there before):
... DNS Servers . . . . . . . . . . . : fec0:0:0:ffff::1%1 fec0:0:0:ffff::2%1 fec0:0:0:ffff::3%1 ...
I've (naively) tried the following commands neither worked:
netsh interface ipv6 delete dnsserver "My Ethernet" all
netsh interface delete dnsserver "My Ethernet" all