curl --request DELETE \
  --url https://us.api.flexprice.io/v1/subscriptions/addon \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: <api-key>' \
  --data '
{
  "addon_association_id": "<string>",
  "reason": "<string>"
}
'

{
  "message": "<string>"
}