public async Task <IActionResult> DeleteObservation([Required] string address)
        {
            if (!_balanceService.IsAddressValid(address))
            {
                return(BadRequest(ErrorResponse.Create("Invalid parameter").AddModelError("address", "Address must be valid")));
            }
            var exists = await _balanceService.IsBalanceObservedAsync(address);

            if (!exists)
            {
                return(NoContent());
            }
            await _balanceService.DeleteBalanceObservationAsync(address);

            return(Ok());
        }