Managed Nodes - Deregister This Managed Nodes is Grayed Out

Hello!

I am trying to remove some EC2 instances off the fleet manager. I found some documentation stating the way to remove it is to deregister from the portal. However, when I follow these instructions, the "Deregister This Managed Node" is grayed out and I unable to click on it. I am not sure on next steps to troubleshoot this. If anyone has idea, I appreciate it!

Thanks!