In order for your declined events to be removed by iCal, you need to associate the Netsuite login email address with your contact record in the Mac Address Book.
The Mac Address Book automatically creates a contact record for the current user. This entry has a “me” icon emblem. For example, in the screen shot below, [...]

We’re very excited to announce the availability of NetSyncX, a product that keeps your Mac in sync with NetSuite. NetSyncX syncs your data between iCal, Apple Mail, Apple Addressbook, and Microsoft Entourage with NetSuite. Please see our web site here for more details on the product. As many of you already know, NetSyncX was previously [...]