From Portal:
1. Sign in to the AWS console
2. In the console, select the specific region
3. Navigate to the ‘AWS Network Firewall’ service.
4. In the left pane under ‘Network Firewall’ click on Firewall.
5. Select desired firewall and click on ‘Firewall details’.
6. Go to ‘change protection’ and click on ‘Edit’.
7. Choose ‘enable’ for Delete protection option and click ‘save’.

From TF:
resource aws_networkfirewall_firewall” “example” {
– delete_protection = false
+ delete_protection = true
}

From Command Line:
In order to set Networks firewall delete protection to TRUE use to following CLI command:
“`aws network-firewall update-firewall-delete-protection –region REGION_NAME –firewall-name FIREWALL_NAME –delete-protection“`
Note: The flag –delete-protection will set the deletion protection to TRUE. The firewall deletion process through the console disables this protection