List Rules by Specification
sudo iptables -S
List Rules as Tables
sudo iptables -L
Delete Rule by Specification
sudo iptables -D INPUT -m conntrack --ctstate INVALID -j DROP
Delete Rule by Chain and Number
sudo iptables -L --line-numbers
sudo iptables -D INPUT 3
Flush All Rules, Delete All Chains, and Accept All
Note: This will effectively disable your firewall. You should only follow this section if you want to start over the configuration of your firewall.
sudo iptables -P INPUT ACCEPT sudo iptables -P FORWARD ACCEPT sudo iptables -P OUTPUT ACCEPT
sudo iptables -t nat -F sudo iptables -t mangle -F sudo iptables -F sudo iptables -X
References
https://www.digitalocean.com/community/tutorials/how-to-list-and-delete-iptables-firewall-rules