If you log in to your account and then click the "Your Account" link, you should get to the page where favorites are managed -- the URL should be something like http://localhost/vufind/MyResearch/Home. >From this page, you can access lists, delete favorites, and edit tags associated with favorites.
VuFind's options for managing user-added metadata are still a bit limited, though -- there is currently no way to delete a list or to remove tags that were added anonymously via the "add tag" option (as opposed to being associated with a specific list of favorites).
The anonymous tag issue is discussed here:
The limitations on list management are discussed here:
Feel free to comment/vote on these issues if you have thoughts on how to deal with these problems or if you want to see them resolved more quickly. I haven't put a lot of time into fixing them yet since there hasn't been a particularly high demand for these social features… but if people want to take the time to discuss the design issues, I'm certainly happy to help with implementation.