public async Task <IActionResult> DeleteCouponUser(int couponID)
{
Guid userID = new Guid(User.FindFirst(ClaimTypes.NameIdentifier)?.Value);
var couponUserEntity = await couponRepository.GetCouponUserAsync(couponID, userID);
if (couponUserEntity == null)
{
return(NotFound());
}
couponRepository.DeleteCouponUser(couponUserEntity);
await couponRepository.SaveAsync();
return(NoContent());
}