Hi,
I agree with above solution,that you just only retrieve 'A' flag Customer before binding(if you added flag for customers),
i.e.
e.g.
select customer from cust_tbl where rec_status='A';
Otherwise you just remove it manually at runtime,i.e.
ddlcustomer.Items.Remove("Customer_id");
if there are multiple then just add it into LIST and remove listItem from dropdown same as above remove statement.
hope this will help you...