Managing Ingress Firewall Rules
Once you have created firewall rules for your static NAT, you can manage them by going into the "IP Addresses" view for the specific address to which these rules apply. This view will display all of the rules that pertain.
To add a new rule, merely click on the "Add Firewall Rule" and fill in the information.
To remove a rule, click on the to the far right of the target rule.
Note: Once a rule has been created, it cannot be modified. If you wish to change a rule, you must first delete the existing rule then recreate it with the changes.
You can remove all of your firewall rules by disabling the static NAT. For more information about disabling static NAT, go HERE