• Disable ipv4 with /etc/sysctl.conf

/etc/sysctl.conf

net.ipv4.conf.all.disable_ipv4 = 1
net.ipv4.conf.default.disable_ipv4 = 1

ip -4 addr show eth0
ip addr del 128.199.175.162/18 dev eth0

sysctl -p

/etc/sysctl.d/99-disable-ipv4.conf

net.ipv4.conf.all.disable_ipv4 = 1
net.ipv4.conf.default.disable_ipv4 = 1
net.ipv4.conf.lo.disable_ipv4 = 0

Disable ipv4 with /etc/sysctl.conf