/// <summary>
/// Asynchronously clears the landmark identified by the provided <paramref name="id" />.
/// </summary>
/// <param name="id">The identifier of the landmark.</param>
/// <returns></returns>
public async Task ClearLandmark(int id)
{
var landmark = _dataContext.Landmarks.FirstOrDefault(l => l.Id == id);
if (landmark != null)
{
landmark.Expiry = DateTimeOffset.Now.AddDays(-1);
await _dataContext.SaveChangesAsync();
}
}