Disable Cloudwatch alarms

• On the alarms page, check the box on the top left to select all
• On the top right, select actions -> alarm actions -> disable
• Repeat for each page

Remove load balancers from ASGs and scale in

• Open each ASG to disable (both even and odd variants)
• Click integrations
• Click edit under load balancing
• Uncheck any linked load balancers
• Save
• Click details on the ASG page
• If the ASG has running instances
  • Click edit on the top right of the page
  • Set desired capacity and min desired capacity to 0

To re-enable everything, applying Terraform is likely the easiest option.