Oracle Certificate Authority policies (those of the Type "OCA Policy") cannot be deleted. They can only be enabled or disabled.
Custom policies can be deleted. When you delete custom policies, they are removed from the policy rules for a particular operation and discarded. To add back deleted custom policies you must register it again with Oracle Certificate Authority. However, if you want to use the custom policy again, then you may prefer to disable it instead of deleting it.
To delete policies:
On the Policy page of the Configuration Management tab, select the Operation type for the policy you want to delete and click Go. A list of policies for that Operation type displays.
Select the policy you want to delete by clicking the radio button adjacent to the Policy Name and click Delete. A message appears confirming that this policy has been deleted.
Restart the Oracle Certificate Authority server for your changes to take effect. See Starting and Stopping Oracle Certificate Authority Server