code: func delEP(stub shim.ChaincodeStubInterface) pb.Response {
  	_, parameters := stub.GetFunctionAndParameters()
  	if len(parameters) < 1 {
  		return shim.Error("No key specified")
  	}
  
  	// set the modified endorsement policy for the key to nil
  	var err error
  	if parameters[0] == "pub" {
  		err = stub.SetStateValidationParameter("pub", nil)
  	} else if parameters[0] == "priv" {
  		err = stub.SetPrivateDataValidationParameter("col", "priv", nil)
  	} else {
  		return shim.Error("Unknown key specified")
  	}
  	if err != nil {
  		return shim.Error(err.Error())
  	}
  
  	return shim.Success([]byte{})
  }
docs: // delEP deletes the state-based endorsement policy for the key altogether