patch https://api.arcadia.com/plug/accounts/
To make updates to a specific account, you can make a PATCH call to the accounts endpoint. Each account can have up to 10 custom data fields associated. Custom data fields are not required. Custom data allows you to organize accounts and tie them back to records in your own system. To update a custom data field, the field must already have a defined label. To define a Custom Data label, you must use the Update Organization Custom Data endpoint.
This endpoint supports Sandbox Mode.