apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/controller/PermissionController.java/PermissionController/removeAppRoleFromUser
class PermissionController:  @PreAuthorize(value = "@permissionValidator.hasManageAppMasterPermission(#appId)")
  @DeleteMapping("/apps/{appId}/roles/{roleType}")
  public ResponseEntity<Void> removeAppRoleFromUser(@PathVariable String appId, @PathVariable String roleType,
                                                    @RequestParam String user) {
    RequestPrecondition.checkArgumentsNotEmpty(user);

    if (!RoleType.isValidRoleType(roleType)) {
      throw new BadRequestException("role type is illegal");
    }
    rolePermissionService.removeRoleFromUsers(RoleUtils.buildAppRoleName(appId, roleType),
        Sets.newHashSet(user), userInfoHolder.getUser().getUserId());
    return ResponseEntity.ok().build();
  }