If you are on a newer version, it is under store settings > Seo Manager tab, you can put anything you like in there as a generic default using the ## site merges...so you can remove ##ITEMNR## from the default settings. This applies across the store.
Additionally I believe you can manually override the title on the product editor too.
If you are on an older version, you can simply request an upgrade.
Ed Sturrock
AmeriCommerce Product Manager