private static void RemoveItemFromList(ICollection<string> list, string item) { if (list == null || string.IsNullOrEmpty(item) || list.Count == 0) { return; } var usersToRemove = list.Where(u => u.Equals(item, StringComparison.OrdinalIgnoreCase)).ToList(); foreach (var u in usersToRemove) { list.Remove(u); } }