I can't unsubscribe FortiGate CNF - Cloud Native Firewall (PAYG with 30-day Free Trial) in my AWS Marketplace -Manage subscriptions

To cancel your FortiGate CNF - Cloud Native Firewall subscription in AWS Marketplace, you need to follow these steps:

1. First, ensure that you have terminated any instances or resources running from this subscription. Canceling a subscription doesn't automatically terminate running resources, and you'll continue to be charged for those.

2. Log in to the AWS Marketplace console at https://console.aws.amazon.com/marketplace.

3. Navigate to "Manage subscriptions" page.

4. For container-based products like FortiGate CNF, you may need to:

• Open the "Delivery method" list and choose "Container Image"
• Find your FortiGate CNF subscription
• Under "Agreement", open the "Actions" list and choose "Cancel subscription"
• In the "Cancel subscription" dialog box, enter "confirm", then choose "Yes, cancel subscription"

If you don't see the cancel option in the Actions menu as shown in your screenshots, you may need to contact AWS Support for assistance with canceling this specific subscription.

Remember that after canceling your subscription, you won't be able to start new instances of the software, but you must also ensure all related resources are terminated to avoid further charges.
Sources
Canceling product subscriptions - AWS Marketplace
I canceled my AWS Marketplace subscription but I got charged | AWS re:Post
Cancel an AWS Marketplace subscription | AWS re:Post