docs: public void dropUser(String name) {
  
          boolean reservedUser = GranteeManager.isReserved(name);
  
          if (reservedUser) {
              throw Error.error(ErrorCode.X_28502, name);
          }
  
          boolean result = granteeManager.removeGrantee(name);
  
          if (!result) {
              throw Error.error(ErrorCode.X_28501, name);
          }
  
          User user = (User) userList.remove(name);
  
          if (user == null) {
              throw Error.error(ErrorCode.X_28501, name);
          }
      }