When systemd-resolved enable ,you will see your /etc/resolv.conf like that: 
nameserver 127.0.0.53
options edns0 trust-ad
search paysmart.local
To disable it ,please run this command: 
systemctl disable systemd-resolved.service
systemctl stop systemd-resolved
And then update your  /etc/resolv.conf  example
echo > /etc/resolv.conf 
tee /etc/resolv.conf << END
nameserver 8.8.4.4
nameserver 8.8.8.8
END
Nguyen Si Nhan