@DELETE @ApiIgnore // until documented
  @Path("{alias}")
  @Produces("text/plain")
  public Response deleteCredential(@Context HttpHeaders headers, @Context UriInfo ui,
                                   @PathParam("alias") String alias) {
    return handleRequest(headers, null, ui, Request.Type.DELETE, createCredentialResource(alias));
  }
Handles: DELETE /clusters/{cluster_name}/credentials/{alias}
Delete a specific credential.

@param headers http headers
@param ui      uri info
@param alias   alias (or credential ID)
@return information regarding the deleted credential
ambari-server/src/main/java/org/apache/ambari/server/api/services/CredentialService.java