You can configure placement end reasons in the Admin Tool under Reference Data > LAC Codes, where the code type is set to End reason.
The Customer Led Configuration uses the specific codes required for the Children Looked After (CLA) / SSDA903 return for English local authorities or the CLAS return (for Scottish local authorities).
If you're required to complete one of these returns, only amend the values if you've been notified by the DfE or Scottish Government. If you're not required to submit either return, you can update the values as needed.