NetworkManager is the program which (via the resolvconf utility) inserts address
resolv.conf. NM inserts that address if and only if it is configured to start an instance of the dnsmasq program to serve as a local forwarding nameserver. That dnsmasq instance listens for queries at address
If you do not want to use a local forwarding nameserver, then configure NetworkManager so it doesn't start a dnsmasq instance nor inserts that address. In
/etc/NetworkManager/NetworkManager.conf comment out the line
sudo nano /etc/NetworkManager/NetworkManager.conf
and restart the NetworkManager service.
sudo restart network-manager
In this mode, NetworkManager updates
/etc/resolv.conf (still via resolvconf) to include the nameserver addresses NetworkManager has for active connections.
If you want to disable the resolvconf mechanism for updating resolv.conf and just use a static resolv.conf file, do the following.
sudo rm -f /etc/resolv.conf # Delete the symbolic link
sudo nano /etc/resolv.conf # Create static file
# Content of static resolv.conf