code: public String deleteScope(String scopeName) throws OAuthException {
          String responseMsg;
          Scope foundScope = DBManagerFactory.getInstance().findScope(scopeName).blockingGet();
          if (foundScope == null) {
              LOG.error("scope does not exist");
              throw new OAuthException(SCOPE_NOT_EXIST, HttpResponseStatus.BAD_REQUEST);
          } else {
              // first, check whether there is a client app registered with that scope
              List<ApplicationInfo> registeredApps = getClientAppsByScope(scopeName);
              if (registeredApps.size() > 0) {
                  responseMsg = SCOPE_USED_BY_APP_MESSAGE;
              } else {
                  boolean ok = DBManagerFactory.getInstance().deleteScope(scopeName).blockingGet();
                  if (ok) {
                      responseMsg = SCOPE_DELETED_OK_MESSAGE;
                  } else {
                      responseMsg = SCOPE_DELETED_NOK_MESSAGE;
                  }
              }
          }
          return responseMsg;
      }
docs: Deletes a scope. If the scope does not exists, returns an error.
  
  @param scopeName scopeName
  @return String message that will be returned in the response