The active portal account must be licensed with the ArcGIS Knowledge user type extension to use Knowledge Graph Server services.
The delete operation is available for a knowledge graph service data model's domains resource. With this operation, you can delete a domain from the data model. Identify the domain you want to delete by specifying the domain name. Use the data model query operation to learn about the domains that are defined in the schema.
You must have sufficient privileges to edit content and editing must be enabled for the knowledge graph service for this operation to be successful. You can enable editing for a knowledge graph service in the same way that you enable it for a hosted feature layer. The knowledge graph service's strict property must not be set to true, which indicates the data model cannot be modified.
Requests and responses
This operation can only be performed by sending an HTTP POST request and receiving a Protocolbuffer Binary Format (PBF)-formatted response. Details of the response parameters are provided in the appropriate .proto file.
The following is a sample POST request to delete a domain named WarehouseType:
POST /webadaptor/rest/services/Hosted/SupplyChain/KnowledgeGraphServer/dataModel/domains/WarehouseType/delete HTTP/1.1 Host: machine.domain.com Content-Type: application/x-www-form-urlencoded Content-Length: 
Create a PBF-formatted response to get feedback from the operation based on the DeleteDomainResponse.proto file.