Actually you are trying to convert a Data Entity to DataContext
I think your code would be something like
public string DeleteCustomer(int ID)
{
using (StoreEntities db = new StoreEntities())
{
Customer customer = db.CustomerSet.Find(ID);
db.CustomerSet.Remove(customer);
db.SaveChanges();
return "Deleted successfully";
}
}
In above code Customer customer = db.CustomerSet.Find(ID);
Customer is your data entity and customer is an instance of Customer