If you just want to keep the Products page in the menu, as a Menu Item, you can delete/unpublish your current page and create a new redirect page to the external one
Alternatively you can keep the Products list page, but remove the Product list widget and redirect to the new one using code behind
on that page.
Another option is to remove the Product list widget and have some Content blocks with for example sample products (image, some data, link, etc) which to link to the new store.
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Sitefinity CMS Ideas&Feedback Portal
and vote to affect the priority of the items