Edit (April 2014): Updated by @paulirish & @sheerun

Package unregistering will be available via bower unregister <package> soon, but for now, you can unregister packages yourself using curl, if the package is hosted on GitHub and you're an owner or collaborator.

curl -X DELETE "https://bower.herokuapp.com/packages/PACKAGE?access_token=TOKEN"

• Where PACKAGE is the package name you want to delete and TOKEN is GitHub's Personal Access Token that you can fetch from here: https://github.com/settings/applications
• A default GitHub Personal Access Token will work -- no permissions necessary
• You need to be an owner or collaborator of the repo and URL needs to be OK.
• You'll likely want to bower cache clean after your change.
• Please remember it is generally considered bad behavior to remove versions of a library that others are depending on. Think twice :)

If the above doesn't work for you, we can handle your case manually (and please post below). And again, soon we'll be addressing the remaining issues so this is much easier for everyone. :) Cheers.