curl --request DELETE \
  --url https://api.reply.io/v3/sequences/{id}/contacts/bulk \
  --header 'Content-Type: application/json' \
  --header 'X-API-Key: <api-key>' \
  --data '
{
  "contactIds": [
    123
  ]
}
'

{
  "title": "Validation Failed",
  "status": 349,
  "detail": "The scheduler with ID 'daily-9am' does not exist in your account",
  "errorCode": 1004
}