curl --request PUT \
  --url 'https://api.hubapi.com/feature-flags/v3/{appId}/flags/{flagName}/portals/{portalId}?hapikey=' \
  --header 'Content-Type: application/json' \
  --data '
{
  "flagState": "ABSENT"
}
'

{
  "appId": 123,
  "flagName": "<string>",
  "flagState": "ABSENT",
  "portalId": 123
}