If you have an untracked listing on Amazon and you want to start selling that product on Amazon, it is a quick and easy process!
Go to the Edit Listings page for the listing by clicking on the 'cog' located under the Amazon icon.
Click on Convert to tracked to convert the untracked listing into a tracked listing.
That's all there is to it!
For more information on untracked listings, here is another article on them!