PKI-04015: Trusted cert cannot be removed

Trying to remove the trusted certificates from the wallet and getting the errors 

$ orapki wallet remove -wallet . -trusted_cert_all
Oracle PKI Tool : Version 11.2.0.4.0 - Production
Copyright (c) 2004, 2013, Oracle and/or its affiliates. All rights reserved.

Enter wallet password:
PKI-04015: Trusted cert cannot be removed. CN=A,O=B,C=C

SOLUTION

$ orapki wallet display -wallet .
Oracle PKI Tool : Version 11.2.0.4.0 - Production
Copyright (c) 2004, 2013, Oracle and/or its affiliates. All rights reserved.

Enter wallet password:
Requested Certificates:
User Certificates:
Subject:        CN=A,O=B,C=C
Trusted Certificates:
Subject:        CN=A,O=B,C=C
$orapki wallet remove -wallet . -trusted_cert -dn "CN=A,O=B,C=C"
$ orapki wallet remove -wallet . -cert_req -dn "CN=A,O=B,C=C"
$ orapki wallet display -wallet .
Oracle PKI Tool : Version 11.2.0.4.0 - Production
Copyright (c) 2004, 2013, Oracle and/or its affiliates. All rights reserved.

Enter wallet password:
Requested Certificates:
User Certificates:
Trusted Certificates: