apollo-adminservice/src/main/java/com/ctrip/framework/apollo/adminservice/controller/NamespaceBranchController.java/NamespaceBranchController/deleteBranch
class NamespaceBranchController:  @Transactional
  @DeleteMapping("/apps/{appId}/clusters/{clusterName}/namespaces/{namespaceName}/branches/{branchName}")
  public void deleteBranch(@PathVariable String appId, @PathVariable String clusterName,
                           @PathVariable String namespaceName, @PathVariable String branchName,
                           @RequestParam("operator") String operator) {

    checkBranch(appId, clusterName, namespaceName, branchName);

    namespaceBranchService
        .deleteBranch(appId, clusterName, namespaceName, branchName, NamespaceBranchStatus.DELETED, operator);

    messageSender.sendMessage(ReleaseMessageKeyGenerator.generate(appId, clusterName, namespaceName),
                              Topics.APOLLO_RELEASE_TOPIC);

  }