I want to remove a comma separated value from the string..
suppose I have a string like this
string x=\"r, v, l, m\"
and i want to
var l = x.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries).ToList();
l.Remove(OfferID.ToString());
x = string.Join(",", l);
Edit: Sorry, you're right. Remove doesn't return the original list. You need multiple statements. But you don't need to trim the end "," implicitly. You can remove that statement from your code as well as the check to see if the item is there or not. The Remove will take it out if it was found or simply return false if it was not found. You don't have to check existence. So remove the TrimEnd from the first and get rid of the second line below:
offIdColl = my_Order.CustomOfferAppliedonOrder; //.TrimEnd(',');
//if (offIdColl.Split(',').Contains(OfferID.ToString()))